diff --git a/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/Analysis.java b/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/Analysis.java
index 465c32ac75..80e93ce22b 100644
--- a/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/Analysis.java
+++ b/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/Analysis.java
@@ -168,9 +168,9 @@ private void findRelatedReferences() {
                     }
 
                     ExecutableElement getter = null, setter = null;
-                    TypeMirror type = null;
-                    String name = null;
-                    if (parameters.size() == 0 && (methodName.startsWith("get") || methodName.startsWith("is"))) {
+                    TypeMirror type;
+                    String name;
+                    if (parameters.isEmpty() && (methodName.startsWith("get") || methodName.startsWith("is"))) {
                         name = BeanUtils.getterName(methodName, null);
                         getter = method;
                         type = method.getReturnType();
@@ -188,8 +188,8 @@ private void findRelatedReferences() {
     }
 
     private List<TypeElement> getTypeHierarchy(TypeElement element) {
-        List<TypeElement> result = new ArrayList<TypeElement>();
-        getAllTypes(element, result, new HashSet<TypeElement>());
+        List<TypeElement> result = new ArrayList<>();
+        getAllTypes(element, result, new HashSet<>());
         return result;
     }
 
diff --git a/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/CodeGenUtils.java b/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/CodeGenUtils.java
index dfe41a881e..2967c71527 100644
--- a/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/CodeGenUtils.java
+++ b/codegen/src/main/java/com/alibaba/fastjson2/internal/processor/CodeGenUtils.java
@@ -495,7 +495,7 @@ public static void getFieldInfo(FieldInfo fieldInfo, JSONField jsonField, boolea
         if (!jsonFieldFormat.isEmpty()) {
             jsonFieldFormat = jsonFieldFormat.trim();
             if (jsonFieldFormat.indexOf('T') != -1 && !jsonFieldFormat.contains("'T'")) {
-                jsonFieldFormat = jsonFieldFormat.replaceAll("T", "'T'");
+                jsonFieldFormat = jsonFieldFormat.replace("T", "'T'");
             }
 
             fieldInfo.format = jsonFieldFormat;
diff --git a/core/src/main/java/com/alibaba/fastjson2/JSONPathSegment.java b/core/src/main/java/com/alibaba/fastjson2/JSONPathSegment.java
index bcfcd47a66..1127990b4a 100644
--- a/core/src/main/java/com/alibaba/fastjson2/JSONPathSegment.java
+++ b/core/src/main/java/com/alibaba/fastjson2/JSONPathSegment.java
@@ -1410,7 +1410,7 @@ public void setCallback(JSONPath.Context context, BiFunction callback) {
             action.accept(object);
         }
 
-        protected boolean shouldRecursive() {
+        boolean shouldRecursive() {
             return nameHashCode == HASH_STAR || nameHashCode == HASH_EMPTY;
         }
 
diff --git a/core/src/main/java/com/alibaba/fastjson2/JSONReader.java b/core/src/main/java/com/alibaba/fastjson2/JSONReader.java
index 9a0a71887b..c075fce6d6 100644
--- a/core/src/main/java/com/alibaba/fastjson2/JSONReader.java
+++ b/core/src/main/java/com/alibaba/fastjson2/JSONReader.java
@@ -2163,7 +2163,7 @@ public void read(Map object, long features) {
                     try {
                         jsonPath = JSONPath.of(reference);
                     } catch (Exception ignored) {
-                        map.put(name, new JSONObject().fluentPut("$ref", reference));
+                        map.put(name, JSONObject.of("$ref", reference));
                         continue;
                     }
                     addResolveTask(map, name, jsonPath);
diff --git a/core/src/main/java/com/alibaba/fastjson2/JSONReaderJSONB.java b/core/src/main/java/com/alibaba/fastjson2/JSONReaderJSONB.java
index 57677df5ac..79598a93ea 100644
--- a/core/src/main/java/com/alibaba/fastjson2/JSONReaderJSONB.java
+++ b/core/src/main/java/com/alibaba/fastjson2/JSONReaderJSONB.java
@@ -81,27 +81,27 @@ final class JSONReaderJSONB
         FIXED_TYPE_SIZE = bytes;
     }
 
-    protected final byte[] bytes;
-    protected final int length;
-    protected final int end;
+    final byte[] bytes;
+    final int length;
+    final int end;
 
-    protected byte type;
-    protected int strlen;
-    protected byte strtype;
-    protected int strBegin;
+    byte type;
+    int strlen;
+    byte strtype;
+    int strBegin;
 
-    protected byte[] valueBytes;
-    protected char[] charBuf;
-    protected final CacheItem cacheItem;
+    byte[] valueBytes;
+    char[] charBuf;
+    final CacheItem cacheItem;
 
-    protected final SymbolTable symbolTable;
+    final SymbolTable symbolTable;
 
-    protected long symbol0Hash;
-    protected int symbol0Begin;
-    protected int symbol0Length;
-    protected byte symbol0StrType;
+    long symbol0Hash;
+    int symbol0Begin;
+    int symbol0Length;
+    byte symbol0StrType;
 
-    protected long[] symbols;
+    long[] symbols;
 
     JSONReaderJSONB(Context ctx, InputStream is) {
         super(ctx, true, false);
@@ -2285,7 +2285,7 @@ public long readValueHashCode() {
         return hashCode;
     }
 
-    protected long getNameHashCode() {
+    long getNameHashCode() {
         int offset = strBegin;
         long nameValue = 0;
         for (int i = 0; i < strlen; offset++) {
@@ -3774,7 +3774,7 @@ public Long readInt64() {
         return int64Value;
     }
 
-    protected String readFixedAsciiString(int strlen) {
+    String readFixedAsciiString(int strlen) {
         byte[] bytes = this.bytes;
         int offset = this.offset;
         String str;
diff --git a/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF16.java b/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF16.java
index 6cb2c7fdc4..a3f66687ef 100644
--- a/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF16.java
+++ b/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF16.java
@@ -2474,7 +2474,7 @@ public final int readInt32Value() {
         }
 
         if (comma = (ch == ',')) {
-            ch = offset == end ? EOI : (char) chars[offset++];
+            ch = offset == end ? EOI : chars[offset++];
             while (ch <= ' ' && ((1L << ch) & SPACE) != 0) {
                 ch = offset == end ? EOI : chars[offset++];
             }
@@ -2571,7 +2571,7 @@ public final long readInt64Value() {
         }
 
         if (comma = (ch == ',')) {
-            ch = offset == end ? EOI : (char) chars[offset++];
+            ch = offset == end ? EOI : chars[offset++];
             while (ch <= ' ' && ((1L << ch) & SPACE) != 0) {
                 ch = offset == end ? EOI : chars[offset++];
             }
@@ -5002,9 +5002,9 @@ public final boolean readBoolValue() {
             wasNull = true;
             offset += 3;
             val = false;
-        } else if (ch == '"') {
+        } else if (ch == '"' || ch == '\'') {
             if (offset + 1 < chars.length
-                    && chars[offset + 1] == '"'
+                    && chars[offset + 1] == ch
             ) {
                 char c0 = chars[offset];
                 offset += 2;
diff --git a/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF8.java b/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF8.java
index 31c07815cf..a182b2642a 100644
--- a/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF8.java
+++ b/core/src/main/java/com/alibaba/fastjson2/JSONReaderUTF8.java
@@ -7152,9 +7152,9 @@ public final boolean readBoolValue() {
             wasNull = true;
             offset += 3;
             val = false;
-        } else if (ch == '"') {
+        } else if (ch == '"' || ch == '\'') {
             if (offset + 1 < bytes.length
-                    && bytes[offset + 1] == '"'
+                    && bytes[offset + 1] == ch
             ) {
                 byte c0 = bytes[offset];
                 offset += 2;
diff --git a/core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF16JDK8UF.java b/core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF16JDK8UF.java
index 1a1c8bbecf..a8bd13e9c5 100644
--- a/core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF16JDK8UF.java
+++ b/core/src/main/java/com/alibaba/fastjson2/JSONWriterUTF16JDK8UF.java
@@ -2,7 +2,6 @@
 
 import com.alibaba.fastjson2.util.JDKUtils;
 
-import static com.alibaba.fastjson2.JSONWriter.Feature.*;
 import static com.alibaba.fastjson2.util.JDKUtils.UNSAFE;
 
 public final class JSONWriterUTF16JDK8UF
diff --git a/core/src/main/java/com/alibaba/fastjson2/codec/DateTimeCodec.java b/core/src/main/java/com/alibaba/fastjson2/codec/DateTimeCodec.java
index 7c81b7647e..ef34af92e7 100644
--- a/core/src/main/java/com/alibaba/fastjson2/codec/DateTimeCodec.java
+++ b/core/src/main/java/com/alibaba/fastjson2/codec/DateTimeCodec.java
@@ -30,7 +30,7 @@ public DateTimeCodec(String format) {
 
     public DateTimeCodec(String format, Locale locale) {
         if (format != null) {
-            format = format.replaceAll("aa", "a");
+            format = format.replace("aa", "a");
         }
 
         this.format = format;
diff --git a/core/src/main/java/com/alibaba/fastjson2/internal/asm/TypeCollector.java b/core/src/main/java/com/alibaba/fastjson2/internal/asm/TypeCollector.java
index 7d8c3ea2b5..42389b2d68 100644
--- a/core/src/main/java/com/alibaba/fastjson2/internal/asm/TypeCollector.java
+++ b/core/src/main/java/com/alibaba/fastjson2/internal/asm/TypeCollector.java
@@ -9,7 +9,7 @@ public class TypeCollector {
     static final Map<String, String> PRIMITIVES;
 
     static {
-        HashMap map = new HashMap();
+        HashMap<String, String> map = new HashMap<>();
         map.put("int", "I");
         map.put("boolean", "Z");
         map.put("byte", "B");
@@ -75,21 +75,22 @@ protected MethodCollector visitMethod(int access, String name, String desc) {
 //    }
 
     private boolean correctTypeName(Type type, String paramTypeName) {
-        String s = type.getClassName();
+        String typeName = type.getClassName();
         // array notation needs cleanup.
         StringBuilder braces = new StringBuilder();
-        while (s.endsWith("[]")) {
+        while (typeName.endsWith("[]")) {
             braces.append('[');
-            s = s.substring(0, s.length() - 2);
+            typeName = typeName.substring(0, typeName.length() - 2);
         }
         if (braces.length() != 0) {
-            if (PRIMITIVES.containsKey(s)) {
-                s = braces.append(PRIMITIVES.get(s)).toString();
+            String symbol = PRIMITIVES.get(typeName);
+            if (symbol != null) {
+                typeName = braces.append(symbol).toString();
             } else {
-                s = braces.append('L').append(s).append(';').toString();
+                typeName = braces.append('L').append(typeName).append(';').toString();
             }
         }
-        return s.equals(paramTypeName);
+        return typeName.equals(paramTypeName);
     }
 
     public String[] getParameterNamesForMethod() {
diff --git a/core/src/main/java/com/alibaba/fastjson2/reader/FieldReaderCollectionMethodReadOnly.java b/core/src/main/java/com/alibaba/fastjson2/reader/FieldReaderCollectionMethodReadOnly.java
index 755a586974..ecd20cf3db 100644
--- a/core/src/main/java/com/alibaba/fastjson2/reader/FieldReaderCollectionMethodReadOnly.java
+++ b/core/src/main/java/com/alibaba/fastjson2/reader/FieldReaderCollectionMethodReadOnly.java
@@ -70,10 +70,6 @@ public void accept(T object, Object value) {
             return;
         }
 
-        if (value == collection) {
-            return;
-        }
-
         Collection values = (Collection) value;
         for (Object item : values) {
             if (item == null) {
diff --git a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderBaseModule.java b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderBaseModule.java
index 639dc1e73d..1cbb54d7a3 100644
--- a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderBaseModule.java
+++ b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderBaseModule.java
@@ -1122,7 +1122,7 @@ private void processJSONField1x(FieldInfo fieldInfo, Annotation annotation) {
                                 format = format.trim();
 
                                 if (format.indexOf('T') != -1 && !format.contains("'T'")) {
-                                    format = format.replaceAll("T", "'T'");
+                                    format = format.replace("T", "'T'");
                                 }
 
                                 fieldInfo.format = format;
@@ -1227,7 +1227,7 @@ private void getFieldInfo(FieldInfo fieldInfo, JSONField jsonField) {
             if (!jsonFieldFormat.isEmpty()) {
                 jsonFieldFormat = jsonFieldFormat.trim();
                 if (jsonFieldFormat.indexOf('T') != -1 && !jsonFieldFormat.contains("'T'")) {
-                    jsonFieldFormat = jsonFieldFormat.replaceAll("T", "'T'");
+                    jsonFieldFormat = jsonFieldFormat.replace("T", "'T'");
                 }
 
                 fieldInfo.format = jsonFieldFormat;
@@ -1257,9 +1257,9 @@ private void getFieldInfo(FieldInfo fieldInfo, JSONField jsonField) {
                 if (fieldInfo.alternateNames == null) {
                     fieldInfo.alternateNames = alternateNames;
                 } else {
-                    Set<String> nameSet = new LinkedHashSet<>();
-                    nameSet.addAll(Arrays.asList(alternateNames));
-                    nameSet.addAll(Arrays.asList(fieldInfo.alternateNames));
+                    Set<String> nameSet = new LinkedHashSet<>(alternateNames.length + fieldInfo.alternateNames.length, 1F);
+                    Collections.addAll(nameSet, alternateNames);
+                    Collections.addAll(nameSet, fieldInfo.alternateNames);
                     fieldInfo.alternateNames = nameSet.toArray(new String[nameSet.size()]);
                 }
             }
diff --git a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderCreator.java b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderCreator.java
index 56db7085e4..24d9919a6d 100644
--- a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderCreator.java
+++ b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderCreator.java
@@ -724,27 +724,26 @@ protected <T> ObjectReader<T> createObjectReaderWithCreator(
 
         boolean[] flags = null;
         int maskCount = 0;
-        if (setterFieldReaders != null) {
-            for (int i = 0; i < setterFieldReaders.length; i++) {
-                FieldReader setterFieldReader = setterFieldReaders[i];
-                if (fieldReaders.containsKey(setterFieldReader.fieldName)) {
-                    if (flags == null) {
-                        flags = new boolean[setterFieldReaders.length];
-                    }
-                    flags[i] = true;
-                    maskCount++;
+        // setterFieldReaders is NOT null here, otherwise Arrays.sort() will throw NPE
+        for (int i = 0; i < setterFieldReaders.length; i++) {
+            FieldReader setterFieldReader = setterFieldReaders[i];
+            if (fieldReaders.containsKey(setterFieldReader.fieldName)) {
+                if (flags == null) {
+                    flags = new boolean[setterFieldReaders.length];
                 }
+                flags[i] = true;
+                maskCount++;
             }
-            if (maskCount > 0) {
-                FieldReader[] array = new FieldReader[setterFieldReaders.length - maskCount];
-                int index = 0;
-                for (int i = 0; i < setterFieldReaders.length; i++) {
-                    if (!flags[i]) {
-                        array[index++] = setterFieldReaders[i];
-                    }
+        }
+        if (maskCount > 0) {
+            FieldReader[] array = new FieldReader[setterFieldReaders.length - maskCount];
+            int index = 0;
+            for (int i = 0; i < setterFieldReaders.length; i++) {
+                if (!flags[i]) {
+                    array[index++] = setterFieldReaders[i];
                 }
-                setterFieldReaders = array;
             }
+            setterFieldReaders = array;
         }
 
         return (ObjectReader<T>) new ObjectReaderNoneDefaultConstructor(
diff --git a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderNoneDefaultConstructor.java b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderNoneDefaultConstructor.java
index a6364be2d8..b274f942b0 100644
--- a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderNoneDefaultConstructor.java
+++ b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderNoneDefaultConstructor.java
@@ -336,10 +336,7 @@ public T readObject(JSONReader jsonReader, Type fieldType, Object fieldName, lon
             }
             for (FieldReader fieldReader : fieldReaders) {
                 if (fieldReader.defaultValue != null) {
-                    Object fieldValue = valueMap.get(fieldReader.fieldNameHash);
-                    if (fieldValue == null) {
-                        valueMap.put(fieldReader.fieldNameHash, fieldReader.defaultValue);
-                    }
+                    valueMap.putIfAbsent(fieldReader.fieldNameHash, fieldReader.defaultValue);
                 }
             }
         }
diff --git a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderRootName.java b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderRootName.java
index 4823c16669..368bed014e 100644
--- a/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderRootName.java
+++ b/core/src/main/java/com/alibaba/fastjson2/reader/ObjectReaderRootName.java
@@ -12,8 +12,8 @@
 
 public final class ObjectReaderRootName<T>
         extends ObjectReaderAdapter<T> {
-    protected final String rootName;
-    protected final long rootNameHashCode;
+    final String rootName;
+    final long rootNameHashCode;
 
     public ObjectReaderRootName(
             Class objectClass,
diff --git a/core/src/main/java/com/alibaba/fastjson2/schema/ArraySchema.java b/core/src/main/java/com/alibaba/fastjson2/schema/ArraySchema.java
index 211f76171d..da18a1cda8 100644
--- a/core/src/main/java/com/alibaba/fastjson2/schema/ArraySchema.java
+++ b/core/src/main/java/com/alibaba/fastjson2/schema/ArraySchema.java
@@ -329,18 +329,7 @@ public JSONObject toJSONObject() {
             object.put("uniqueItems", uniqueItems);
         }
 
-        if (allOf != null) {
-            object.put("allOf", allOf);
-        }
-
-        if (anyOf != null) {
-            object.put("anyOf", anyOf);
-        }
-
-        if (oneOf != null) {
-            object.put("oneOf", oneOf);
-        }
-        return object;
+        return injectIfPresent(object, allOf, anyOf, oneOf);
     }
 
     @Override
diff --git a/core/src/main/java/com/alibaba/fastjson2/schema/JSONSchema.java b/core/src/main/java/com/alibaba/fastjson2/schema/JSONSchema.java
index 77204dd3da..1374fe6392 100644
--- a/core/src/main/java/com/alibaba/fastjson2/schema/JSONSchema.java
+++ b/core/src/main/java/com/alibaba/fastjson2/schema/JSONSchema.java
@@ -641,18 +641,10 @@ public static JSONSchema of(JSONObject input, JSONSchema parent) {
 
     static AnyOf anyOf(JSONObject input, Class type) {
         JSONArray array = input.getJSONArray("anyOf");
-        if (array == null || array.isEmpty()) {
-            return null;
-        }
-        JSONSchema[] items = new JSONSchema[array.size()];
-        for (int i = 0; i < items.length; i++) {
-            items[i] = JSONSchema.of(array.getJSONObject(i), type);
-        }
-
-        return new AnyOf(items);
+        return anyOf(array, type);
     }
 
-    static AnyOf anyOf(JSONArray array, Class type) {
+    static JSONSchema[] makeSchemaItems(JSONArray array, Class type) {
         if (array == null || array.isEmpty()) {
             return null;
         }
@@ -660,46 +652,28 @@ static AnyOf anyOf(JSONArray array, Class type) {
         for (int i = 0; i < items.length; i++) {
             items[i] = JSONSchema.of(array.getJSONObject(i), type);
         }
+        return items;
+    }
 
-        return new AnyOf(items);
+    static AnyOf anyOf(JSONArray array, Class type) {
+        JSONSchema[] items = makeSchemaItems(array, type);
+        return items == null ? null : new AnyOf(items);
     }
 
     static AllOf allOf(JSONObject input, Class type) {
         JSONArray array = input.getJSONArray("allOf");
-        if (array == null || array.isEmpty()) {
-            return null;
-        }
-
-        JSONSchema[] items = new JSONSchema[array.size()];
-        for (int i = 0; i < items.length; i++) {
-            items[i] = JSONSchema.of(array.getJSONObject(i), type);
-        }
-        return new AllOf(items);
+        JSONSchema[] items = makeSchemaItems(array, type);
+        return items == null ? null : new AllOf(items);
     }
 
     static OneOf oneOf(JSONObject input, Class type) {
         JSONArray array = input.getJSONArray("oneOf");
-        if (array == null || array.isEmpty()) {
-            return null;
-        }
-
-        JSONSchema[] items = new JSONSchema[array.size()];
-        for (int i = 0; i < items.length; i++) {
-            items[i] = JSONSchema.of(array.getJSONObject(i), type);
-        }
-        return new OneOf(items);
+        return oneOf(array, type);
     }
 
     static OneOf oneOf(JSONArray array, Class type) {
-        if (array == null || array.isEmpty()) {
-            return null;
-        }
-
-        JSONSchema[] items = new JSONSchema[array.size()];
-        for (int i = 0; i < items.length; i++) {
-            items[i] = JSONSchema.of(array.getJSONObject(i), type);
-        }
-        return new OneOf(items);
+        JSONSchema[] items = makeSchemaItems(array, type);
+        return items == null ? null : new OneOf(items);
     }
 
     public String getTitle() {
@@ -943,4 +917,19 @@ public void write(JSONWriter jsonWriter,
     public void accept(Predicate<JSONSchema> v) {
         v.test(this);
     }
+
+    static JSONObject injectIfPresent(JSONObject object, AllOf allOf, AnyOf anyOf, OneOf oneOf) {
+        if (allOf != null) {
+            object.put("allOf", allOf);
+        }
+
+        if (anyOf != null) {
+            object.put("anyOf", anyOf);
+        }
+
+        if (oneOf != null) {
+            object.put("oneOf", oneOf);
+        }
+        return object;
+    }
 }
diff --git a/core/src/main/java/com/alibaba/fastjson2/schema/ObjectSchema.java b/core/src/main/java/com/alibaba/fastjson2/schema/ObjectSchema.java
index 43c8478d73..76dde54636 100644
--- a/core/src/main/java/com/alibaba/fastjson2/schema/ObjectSchema.java
+++ b/core/src/main/java/com/alibaba/fastjson2/schema/ObjectSchema.java
@@ -673,19 +673,7 @@ public JSONObject toJSONObject() {
             object.put("else", elseSchema);
         }
 
-        if (allOf != null) {
-            object.put("allOf", allOf);
-        }
-
-        if (anyOf != null) {
-            object.put("anyOf", anyOf);
-        }
-
-        if (oneOf != null) {
-            object.put("oneOf", oneOf);
-        }
-
-        return object;
+        return injectIfPresent(object, allOf, anyOf, oneOf);
     }
 
     public void accept(Predicate<JSONSchema> v) {
diff --git a/core/src/main/java/com/alibaba/fastjson2/schema/StringSchema.java b/core/src/main/java/com/alibaba/fastjson2/schema/StringSchema.java
index f9baa630f6..ad548f5ad9 100644
--- a/core/src/main/java/com/alibaba/fastjson2/schema/StringSchema.java
+++ b/core/src/main/java/com/alibaba/fastjson2/schema/StringSchema.java
@@ -64,7 +64,7 @@ public final class StringSchema
             Object property = input.get("enum");
             if (property instanceof Collection) {
                 Collection enums = (Collection) property;
-                enumValues = new LinkedHashSet<>(enums.size());
+                enumValues = new LinkedHashSet<>(enums.size(), 1F);
                 enumValues.addAll((Collection<String>) enums);
             } else if (property instanceof Object[]) {
                 enumValues = input.getObject("enum", TypeReference.collectionType(LinkedHashSet.class, String.class));
diff --git a/core/src/main/java/com/alibaba/fastjson2/util/DateUtils.java b/core/src/main/java/com/alibaba/fastjson2/util/DateUtils.java
index dd268ed9f3..a8057fc378 100644
--- a/core/src/main/java/com/alibaba/fastjson2/util/DateUtils.java
+++ b/core/src/main/java/com/alibaba/fastjson2/util/DateUtils.java
@@ -1053,7 +1053,7 @@ public static LocalDate parseLocalDate8(char[] str, int off) {
         } else if (c1 == '-' && str[off + 5] == '-') {
             // d-MMM-yy
             dom = digit1(str, off);
-            month = DateUtils.month((char) str[off + 2], c3, c4);
+            month = DateUtils.month(str[off + 2], c3, c4);
             year = digit2(str, off + 6);
             if (year != -1) {
                 year += 2000;
@@ -1325,7 +1325,7 @@ public static LocalDate parseLocalDate10(char[] str, int off) {
         } else if (c1 == ' ' && c5 == ' ') {
             // d MMM yyyy
             dom = digit1(str, off);
-            month = DateUtils.month(c2, (char) str[off + 3], c4);
+            month = DateUtils.month(c2, str[off + 3], c4);
             year = digit4(str, off + 6);
         } else {
             return null;
@@ -1677,7 +1677,7 @@ public static LocalDateTime parseLocalDateTime17(char[] str, int off) {
         char c15 = str[off + 15];
         char c16 = str[off + 16];
 
-        int year, month, dom, hour, minute, second = 0, nanoOfSecond = 0;
+        int year, month, dom, hour, minute, second, nanoOfSecond = 0;
         if (c4 == '-' && c7 == '-' && (c10 == 'T' || c10 == ' ') && c13 == ':' && c16 == 'Z') {
             year = digit4(str, off);
             month = digit2(str, off + 5);
@@ -5657,23 +5657,7 @@ public static long parseMillisYMDHMS19(String str, ZoneId zoneId) {
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400
                     + hour * 3600
                     + minute * 60
@@ -5702,6 +5686,26 @@ public static long parseMillisYMDHMS19(String str, ZoneId zoneId) {
         return (utcSeconds - zoneOffsetTotalSeconds) * 1000L;
     }
 
+    private static long calcEpochDay(int year, int month, int dom) {
+        final int DAYS_PER_CYCLE = 146097;
+        final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
+
+        long total = (365 * year)
+                + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
+                + ((367 * month - 362) / 12)
+                + (dom - 1);
+
+        if (month > 2) {
+            total--;
+            boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
+            if (!leapYear) {
+                total--;
+            }
+        }
+
+        return total - DAYS_0000_TO_1970;
+    }
+
     static long parseMillis19(
             String str,
             ZoneId zoneId,
@@ -5979,23 +5983,7 @@ static long parseMillis19(
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400
                     + hour * 3600
                     + minute * 60
@@ -6181,23 +6169,7 @@ static long parseMillis10(
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400;
         }
 
@@ -6586,23 +6558,7 @@ public static long parseMillis19(String str, ZoneId zoneId) {
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400
                     + hour * 3600
                     + minute * 60
@@ -6937,23 +6893,7 @@ public static long parseMillis19(byte[] bytes, int off, ZoneId zoneId) {
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400
                     + hour * 3600
                     + minute * 60
@@ -7289,23 +7229,7 @@ public static long parseMillis19(char[] bytes, int off, ZoneId zoneId) {
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400
                     + hour * 3600
                     + minute * 60
@@ -7566,23 +7490,7 @@ public static long millis(
 
         long utcSeconds;
         {
-            final int DAYS_PER_CYCLE = 146097;
-            final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-            long total = (365 * year)
-                    + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                    + ((367 * month - 362) / 12)
-                    + (dom - 1);
-
-            if (month > 2) {
-                total--;
-                boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-                if (!leapYear) {
-                    total--;
-                }
-            }
-
-            long epochDay = total - DAYS_0000_TO_1970;
+            long epochDay = calcEpochDay(year, month, dom);
             utcSeconds = epochDay * 86400
                     + hour * 3600
                     + minute * 60
@@ -7620,23 +7528,7 @@ public static long utcSeconds(
             int minute,
             int second
     ) {
-        final int DAYS_PER_CYCLE = 146097;
-        final long DAYS_0000_TO_1970 = (DAYS_PER_CYCLE * 5L) - (30L * 365L + 7L);
-
-        long total = (365 * year)
-                + ((year + 3) / 4 - (year + 99) / 100 + (year + 399) / 400)
-                + ((367 * month - 362) / 12)
-                + (dom - 1);
-
-        if (month > 2) {
-            total--;
-            boolean leapYear = (year & 3) == 0 && ((year % 100) != 0 || (year % 400) == 0);
-            if (!leapYear) {
-                total--;
-            }
-        }
-
-        long epochDay = total - DAYS_0000_TO_1970;
+        long epochDay = calcEpochDay(year, month, dom);
         return epochDay * 86400
                 + hour * 3600
                 + minute * 60
diff --git a/core/src/main/java/com/alibaba/fastjson2/util/FDBigInteger.java b/core/src/main/java/com/alibaba/fastjson2/util/FDBigInteger.java
index e90ed00ad7..71bcfb2b6e 100644
--- a/core/src/main/java/com/alibaba/fastjson2/util/FDBigInteger.java
+++ b/core/src/main/java/com/alibaba/fastjson2/util/FDBigInteger.java
@@ -164,7 +164,7 @@ private FDBigInteger mult(FDBigInteger other) {
     }
 
     private static void mult(int[] src, int srcLen, int value, int[] dst) {
-        long val = value & 0XFFFFFFFFL;
+        final long val = value & 0XFFFFFFFFL;
         long carry = 0;
         for (int i = 0; i < srcLen; i++) {
             long product = (src[i] & 0XFFFFFFFFL) * val + carry;
@@ -188,16 +188,9 @@ private static void mult(int[] s1, int s1Len, int[] s2, int s2Len, int[] dst) {
     }
 
     private static void mult(int[] src, int srcLen, int v0, int v1, int[] dst) {
-        long v = v0 & 0XFFFFFFFFL;
+        mult(src, srcLen, v0, dst);
+        long v = v1 & 0XFFFFFFFFL;
         long carry = 0;
-        for (int j = 0; j < srcLen; j++) {
-            long product = v * (src[j] & 0XFFFFFFFFL) + carry;
-            dst[j] = (int) product;
-            carry = product >>> 32;
-        }
-        dst[srcLen] = (int) carry;
-        v = v1 & 0XFFFFFFFFL;
-        carry = 0;
         for (int j = 0; j < srcLen; j++) {
             long product = (dst[j + 1] & 0XFFFFFFFFL) + v * (src[j] & 0XFFFFFFFFL) + carry;
             dst[j + 1] = (int) product;
diff --git a/core/src/main/java/com/alibaba/fastjson2/util/IOUtils.java b/core/src/main/java/com/alibaba/fastjson2/util/IOUtils.java
index 8d353ac57f..9fcab7d077 100644
--- a/core/src/main/java/com/alibaba/fastjson2/util/IOUtils.java
+++ b/core/src/main/java/com/alibaba/fastjson2/util/IOUtils.java
@@ -1037,10 +1037,8 @@ public static int writeInt64(char[] buf, int pos, final long value) {
         long i;
         if (value < 0) {
             if (value == Long.MIN_VALUE) {
-                if (value == Long.MIN_VALUE) {
-                    System.arraycopy(MIN_LONG_CHARS, 0, buf, pos, MIN_LONG_CHARS.length);
-                    return pos + MIN_LONG_CHARS.length;
-                }
+                System.arraycopy(MIN_LONG_CHARS, 0, buf, pos, MIN_LONG_CHARS.length);
+                return pos + MIN_LONG_CHARS.length;
             }
             i = -value;
             putChar(buf, pos++, '-');
diff --git a/core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java b/core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java
index e83f4033e9..fbf58e781c 100644
--- a/core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java
+++ b/core/src/main/java/com/alibaba/fastjson2/util/TypeUtils.java
@@ -1001,7 +1001,7 @@ public static double doubleValue(boolean isNegative, int decExp, char[] digits,
                 if (ieeeBits == 0 || ieeeBits == DOUBLE_EXP_BIT_MASK) { // 0.0 or Double.POSITIVE_INFINITY
                     break; // oops. Fell off end of range.
                 }
-                continue; // try again.
+                // try again.
             }
         }
         if (isNegative) {
@@ -1404,9 +1404,10 @@ public static <T> T cast(Object obj, Type type) {
         return cast(obj, type, JSONFactory.getDefaultObjectReaderProvider());
     }
 
+    @SuppressWarnings({ "rawtypes", "unchecked" })
     public static <T> T cast(Object obj, Type type, ObjectReaderProvider provider) {
         if (type instanceof Class) {
-            return (T) cast(obj, (Class) type, provider);
+            return cast(obj, (Class<T>) type, provider);
         }
 
         if (obj instanceof Collection) {
@@ -1429,6 +1430,7 @@ public static <T> T cast(Object obj, Class<T> targetClass) {
         return cast(obj, targetClass, JSONFactory.getDefaultObjectReaderProvider());
     }
 
+    @SuppressWarnings({ "rawtypes", "unchecked" })
     public static <T> T cast(Object obj, Class<T> targetClass, ObjectReaderProvider provider) {
         if (obj == null) {
             return null;
diff --git a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterBaseModule.java b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterBaseModule.java
index 899fcacd85..55b45fbbe7 100644
--- a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterBaseModule.java
+++ b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterBaseModule.java
@@ -980,7 +980,7 @@ private void loadJsonFieldFormat(FieldInfo fieldInfo, String jsonFieldFormat) {
                 jsonFieldFormat = jsonFieldFormat.trim();
 
                 if (jsonFieldFormat.indexOf('T') != -1 && !jsonFieldFormat.contains("'T'")) {
-                    jsonFieldFormat = jsonFieldFormat.replaceAll("T", "'T'");
+                    jsonFieldFormat = jsonFieldFormat.replace("T", "'T'");
                 }
 
                 if (!jsonFieldFormat.isEmpty()) {
diff --git a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreator.java b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreator.java
index d2425f2093..b6c5ffadec 100644
--- a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreator.java
+++ b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreator.java
@@ -492,7 +492,7 @@ boolean record = BeanUtils.isRecord(objectClass);
                         } else if (firstChar >= 'a' && firstChar <= 'z') {
                             sameFieldName = (char) (firstChar - 32) + fieldName.substring(1);
                         }
-                        if (sameFieldName != null && fieldWriterMap.containsKey(sameFieldName)) {
+                        if (sameFieldName != null) {
                             fieldWriterMap.remove(sameFieldName);
                         }
                     }
@@ -519,7 +519,7 @@ boolean record = BeanUtils.isRecord(objectClass);
                     SUPER,
                     superType,
                     objectClass.getSuperclass(),
-                    o -> o
+                    Function.identity()
             );
             fieldWriters.add(superWriter);
         }
diff --git a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java
index 92d22a4d18..b7f32d3347 100644
--- a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java
+++ b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterCreatorASM.java
@@ -355,7 +355,7 @@ boolean record = BeanUtils.isRecord(objectClass);
                         } else if (firstChar >= 'a' && firstChar <= 'z') {
                             sameFieldName = (char) (firstChar - 32) + fieldName.substring(1);
                         }
-                        if (sameFieldName != null && fieldWriterMap.containsKey(sameFieldName)) {
+                        if (sameFieldName != null) {
                             fieldWriterMap.remove(sameFieldName);
                         }
                     }
diff --git a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterImplDouble.java b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterImplDouble.java
index d4430b1f1f..03c6543afb 100644
--- a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterImplDouble.java
+++ b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterImplDouble.java
@@ -40,7 +40,7 @@ public void write(JSONWriter jsonWriter, Object object, Object fieldName, Type f
         DecimalFormat decimalFormat = this.format;
         if (decimalFormat == null) {
             String format = jsonWriter.getContext().getDateFormat();
-            if (format != null && format.indexOf("#") != -1) {
+            if (format != null && format.indexOf('#') != -1) {
                 decimalFormat = new DecimalFormat(format);
             }
         }
diff --git a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterProvider.java b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterProvider.java
index 6e8b783ca7..143b28b88b 100644
--- a/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterProvider.java
+++ b/core/src/main/java/com/alibaba/fastjson2/writer/ObjectWriterProvider.java
@@ -394,14 +394,11 @@ private ObjectWriter getObjectWriterInternal(Type objectType, Class objectClass,
             if (fieldBased) {
                 fieldBased = false;
                 objectWriter = cacheFieldBased.get(objectType);
-                if (objectWriter != null) {
-                    return objectWriter;
-                }
             } else {
                 objectWriter = cache.get(objectType);
-                if (objectWriter != null) {
-                    return objectWriter;
-                }
+            }
+            if (objectWriter != null) {
+                return objectWriter;
             }
         }
 
diff --git a/core/src/test/java/com/alibaba/fastjson2/issues_3200/Issue3283.java b/core/src/test/java/com/alibaba/fastjson2/issues_3200/Issue3283.java
new file mode 100644
index 0000000000..fbcd107eb9
--- /dev/null
+++ b/core/src/test/java/com/alibaba/fastjson2/issues_3200/Issue3283.java
@@ -0,0 +1,38 @@
+package com.alibaba.fastjson2.issues_3200;
+
+import com.alibaba.fastjson2.JSONObject;
+import org.junit.Test;
+import org.junit.jupiter.api.Assertions;
+
+public class Issue3283 {
+    static class Bean {
+        private boolean test;
+
+        public boolean isTest() {
+            return test;
+        }
+
+        public void setTest(boolean test) {
+            this.test = test;
+        }
+    }
+
+    @Test
+    public void singleQuote() {
+        String text = "{'test': 'true'}";
+        Bean bean = JSONObject.parseObject(text, Bean.class);
+        Assertions.assertTrue(bean.isTest());
+
+        text = "{'test': ''}";
+        bean = JSONObject.parseObject(text, Bean.class);
+        Assertions.assertFalse(bean.isTest());
+
+        text = "{'test': 'Y'}";
+        bean = JSONObject.parseObject(text, Bean.class);
+        Assertions.assertTrue(bean.isTest());
+
+        text = "{'test': '1'}";
+        bean = JSONObject.parseObject(text, Bean.class);
+        Assertions.assertTrue(bean.isTest());
+    }
+}
diff --git a/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest.java b/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest.java
index ce223095e3..9c7179d9b5 100644
--- a/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest.java
+++ b/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest.java
@@ -82,7 +82,7 @@ public void readUUID() {
                 uuid,
                 JSONReader.ofJSONB(
                         JSONB.toBytes(
-                                str.replaceAll("-", "")
+                                str.replace("-", "")
                         )
                 ).readUUID()
         );
diff --git a/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest3.java b/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest3.java
index dc55e3c702..8ffa442827 100644
--- a/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest3.java
+++ b/core/src/test/java/com/alibaba/fastjson2/primitves/UUIDTest3.java
@@ -17,7 +17,7 @@ public class UUIDTest3 {
     };
 
     static String toString(UUID id) {
-        return id.toString().replaceAll("-", "");
+        return id.toString().replace("-", "");
     }
 
     @Test
diff --git a/core/src/test/java/com/alibaba/fastjson2_demo/Int2Decoder.java b/core/src/test/java/com/alibaba/fastjson2_demo/Int2Decoder.java
index e0627d4c79..bc9910d886 100644
--- a/core/src/test/java/com/alibaba/fastjson2_demo/Int2Decoder.java
+++ b/core/src/test/java/com/alibaba/fastjson2_demo/Int2Decoder.java
@@ -12,9 +12,9 @@ public void acceptField(JSONReader jsonReader, Int2 object, long hashCode) {
         if (hashCode == V0) {
             int fieldInt = jsonReader.readInt32Value();
             object.setV0000(fieldInt);
-        } else if (hashCode == V0) {
+        } else if (hashCode == V1) {
             int fieldInt = jsonReader.readInt32Value();
-            object.setV0000(fieldInt);
+            object.setV0001(fieldInt);
         }
     }
 }
diff --git a/example-spring-test/src/main/java/com/alibaba/fastjson2/example/springtest/controller/TestController.java b/example-spring-test/src/main/java/com/alibaba/fastjson2/example/springtest/controller/TestController.java
index 454d84af1d..bd1c8f6b4a 100644
--- a/example-spring-test/src/main/java/com/alibaba/fastjson2/example/springtest/controller/TestController.java
+++ b/example-spring-test/src/main/java/com/alibaba/fastjson2/example/springtest/controller/TestController.java
@@ -24,8 +24,7 @@ public User test(User user) {
     @GetMapping(value = "/hello", produces = "text/html")
     public void hello(HttpServletResponse response) {
         //返回一个html测试页面
-        try (ServletOutputStream servletOutputStream = response.getOutputStream();
-        ) {
+        try (ServletOutputStream servletOutputStream = response.getOutputStream()) {
             ClassPathResource classPathResource = new ClassPathResource("hello.html");
             servletOutputStream.write(classPathResource.readBytes());
         } catch (IOException e) {
diff --git a/extension-jaxrs/extension-jaxrs-javax/src/main/java/com/alibaba/fastjson2/support/jaxrs/javax/FastJson2Provider.java b/extension-jaxrs/extension-jaxrs-javax/src/main/java/com/alibaba/fastjson2/support/jaxrs/javax/FastJson2Provider.java
index 8ca7fba943..e3d6b46fc5 100644
--- a/extension-jaxrs/extension-jaxrs-javax/src/main/java/com/alibaba/fastjson2/support/jaxrs/javax/FastJson2Provider.java
+++ b/extension-jaxrs/extension-jaxrs-javax/src/main/java/com/alibaba/fastjson2/support/jaxrs/javax/FastJson2Provider.java
@@ -73,7 +73,7 @@ public class FastJson2Provider
      * Can serialize/deserialize all types.
      */
     public FastJson2Provider() {
-        this((Class<?>[]) null);
+        this(null);
     }
 
     /**
diff --git a/extension-solon/src/main/java/com/alibaba/fastjson2/support/solon/Fastjson2ActionExecutor.java b/extension-solon/src/main/java/com/alibaba/fastjson2/support/solon/Fastjson2ActionExecutor.java
index 1ce8e7463e..b31ddce36d 100644
--- a/extension-solon/src/main/java/com/alibaba/fastjson2/support/solon/Fastjson2ActionExecutor.java
+++ b/extension-solon/src/main/java/com/alibaba/fastjson2/support/solon/Fastjson2ActionExecutor.java
@@ -81,7 +81,7 @@ protected Object changeValue(Context ctx, ParamWrap p, int pi, Class<?> pt, Obje
             return super.changeValue(ctx, p, pi, pt, bodyObj);
         }
 
-        if (p.spec().isRequiredBody() == false && ctx.paramMap().containsKey(p.spec().getName())) {
+        if (!p.spec().isRequiredBody() && ctx.paramMap().containsKey(p.spec().getName())) {
             //If path、queryString?
             return super.changeValue(ctx, p, pi, pt, bodyObj);
         }
@@ -93,7 +93,7 @@ protected Object changeValue(Context ctx, ParamWrap p, int pi, Class<?> pt, Obje
         if (bodyObj instanceof JSONObject) {
             JSONObject tmp = (JSONObject) bodyObj;
 
-            if (p.spec().isRequiredBody() == false) {
+            if (!p.spec().isRequiredBody()) {
                 //
                 //If there is no body requirement; Try to find by attribute
                 //
diff --git a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPointReader.java b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPointReader.java
index 1e8a4db35a..3efa0d34d8 100644
--- a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPointReader.java
+++ b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPointReader.java
@@ -28,11 +28,7 @@ public GeoJsonPoint readObject(JSONReader jsonReader, Type fieldType, Object fie
         jsonReader.nextIfObjectStart();
 
         double x = 0, y = 0;
-        for (; ; ) {
-            if (jsonReader.nextIfObjectEnd()) {
-                break;
-            }
-
+        while (!jsonReader.nextIfObjectEnd()) {
             long nameHashCode = jsonReader.readFieldNameHashCode();
             if (nameHashCode == HASH_TYPE) {
                 long valueHashCode = jsonReader.readValueHashCode();
diff --git a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPolygonReader.java b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPolygonReader.java
index cf2932c07b..37bebeccb5 100644
--- a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPolygonReader.java
+++ b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/data/mongodb/GeoJsonPolygonReader.java
@@ -33,11 +33,7 @@ public GeoJsonPolygon readObject(JSONReader jsonReader, Type fieldType, Object f
 
         List<Point> points = new ArrayList<>();
 
-        for (; ; ) {
-            if (jsonReader.nextIfObjectEnd()) {
-                break;
-            }
-
+        while (!jsonReader.nextIfObjectEnd()) {
             long nameHashCode = jsonReader.readFieldNameHashCode();
             if (nameHashCode == HASH_TYPE) {
                 long valueHashCode = jsonReader.readValueHashCode();
diff --git a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/http/codec/Fastjson2Encoder.java b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/http/codec/Fastjson2Encoder.java
index 836907d2ce..70b47dc821 100644
--- a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/http/codec/Fastjson2Encoder.java
+++ b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/http/codec/Fastjson2Encoder.java
@@ -81,7 +81,7 @@ public DataBuffer encodeValue(@Nullable Object value,
     }
 
     private void configFilter(JSONWriter.Context context, Filter... filters) {
-        if (filters == null || filters.length == 0) {
+        if (filters == null) {
             return;
         }
         for (Filter filter : filters) {
diff --git a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/webservlet/view/FastJsonJsonView.java b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/webservlet/view/FastJsonJsonView.java
index 6d7d350af9..90fa4a3900 100644
--- a/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/webservlet/view/FastJsonJsonView.java
+++ b/extension-spring5/src/main/java/com/alibaba/fastjson2/support/spring/webservlet/view/FastJsonJsonView.java
@@ -11,9 +11,7 @@
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Set;
+import java.util.*;
 
 /**
  * Fastjson for Spring MVC View.
@@ -151,29 +149,34 @@ public void setUpdateContentLength(boolean updateContentLength) {
      * @return the object to be rendered
      */
     protected Object filterModel(Map<String, Object> model) {
-        Map<String, Object> result = new HashMap<String, Object>(model.size());
-        Set<String> renderedAttributes = !CollectionUtils.isEmpty(this.renderedAttributes) ? //
-                this.renderedAttributes //
-                : model.keySet();
+        int expectSize = model.size();
+        final Set<String> renderedKeys;
+        if (CollectionUtils.isEmpty(this.renderedAttributes)) {
+            renderedKeys = null;
+        } else {
+            renderedKeys = this.renderedAttributes;
+            expectSize = renderedKeys.size();
+        }
+        // This is a high frequency operation and is worth optimizing separately.
+        if (expectSize == 1 && extractValueFromSingleKeyModel) {
+            Object value = renderedKeys != null
+                    ? model.get(renderedKeys.iterator().next())
+                    : model.values().iterator().next();
+            return value instanceof BindingResult ? Collections.emptyMap() : value;
+        }
 
+        final Map<String, Object> result = new HashMap<>(expectSize, 1F);
         for (Map.Entry<String, Object> entry : model.entrySet()) {
             if (!(entry.getValue() instanceof BindingResult)
-                    && renderedAttributes.contains(entry.getKey())) {
+                    && (renderedKeys == null || renderedKeys.contains(entry.getKey()))) {
                 result.put(entry.getKey(), entry.getValue());
             }
         }
-        if (extractValueFromSingleKeyModel) {
-            if (result.size() == 1) {
-                for (Map.Entry<String, Object> entry : result.entrySet()) {
-                    return entry.getValue();
-                }
+        if (extractValueFromSingleKeyModel && result.size() == 1) {
+            for (Map.Entry<String, Object> entry : result.entrySet()) {
+                return entry.getValue();
             }
         }
         return result;
     }
-
-    @Override
-    protected void setResponseContentType(HttpServletRequest request, HttpServletResponse response) {
-        super.setResponseContentType(request, response);
-    }
 }
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/AwtRederModule.java b/extension/src/main/java/com/alibaba/fastjson2/support/AwtRederModule.java
index 03784ca54e..543591a09d 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/AwtRederModule.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/AwtRederModule.java
@@ -72,7 +72,7 @@ static class ColorCreator
         public Color apply(Map<Long, Object> values) {
             Integer rgb = (Integer) values.get(HASH_RGB);
             if (rgb != null) {
-                return new Color(rgb.intValue());
+                return new Color(rgb);
             }
 
             Integer r = (Integer) values.get(HASH_R);
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowByteArrayConsumer.java b/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowByteArrayConsumer.java
index 29d937b8ec..def961e299 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowByteArrayConsumer.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowByteArrayConsumer.java
@@ -11,6 +11,7 @@
 import org.apache.arrow.vector.types.pojo.Schema;
 
 import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.nio.charset.Charset;
 import java.util.List;
 import java.util.function.Consumer;
@@ -64,7 +65,7 @@ public void afterRow(int row) {
                 if (committer != null) {
                     Long[] blocks = new Long[blockIndex + 1];
                     for (int i = 0; i <= blockIndex; i++) {
-                        blocks[i] = Long.valueOf(i);
+                        blocks[i] = (long) i;
                     }
                     committer.accept(blocks);
                 }
@@ -91,7 +92,7 @@ public void allocateNew(int blockSize) {
                 ((FixedWidthVector) vector).allocateNew(blockSize);
             } else if (vector instanceof VariableWidthVector) {
                 VariableWidthVector variableWidthVector = (VariableWidthVector) vector;
-                variableWidthVector.allocateNew(varcharValueSize * blockSize, blockSize);
+                variableWidthVector.allocateNew((long) varcharValueSize * blockSize, blockSize);
                 valueCapacities[i] = variableWidthVector.getValueCapacity();
             } else {
                 throw new JSONException("TODO");
@@ -150,7 +151,7 @@ public void accept(int row, int column, byte[] bytes, int off, int len, Charset
             Decimal256Vector decimalVector = (Decimal256Vector) vector;
             int scale = decimalVector.getScale();
             if (decimal.scale() != scale) {
-                decimal = decimal.setScale(scale);
+                decimal = decimal.setScale(scale, RoundingMode.CEILING);
             }
             decimalVector.set(row, decimal);
             return;
@@ -195,7 +196,7 @@ public void accept(int row, int column, byte[] bytes, int off, int len, Charset
         if (vector instanceof BitVector) {
             Boolean value = TypeUtils.parseBoolean(bytes, off, len);
             if (value != null) {
-                int intValue = value.booleanValue() ? 1 : 0;
+                int intValue = value ? 1 : 0;
                 ((BitVector) vector).set(row, intValue);
             }
             return;
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowUtils.java b/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowUtils.java
index 202dba3b7e..f19118e1d7 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowUtils.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/arrow/ArrowUtils.java
@@ -10,6 +10,7 @@
 
 import java.io.IOException;
 import java.math.BigDecimal;
+import java.math.RoundingMode;
 import java.nio.ByteOrder;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
@@ -167,11 +168,9 @@ public static void setValue(FieldVector vector, int row, String value) {
         }
 
         if (vector instanceof BitVector) {
-            Boolean booleanValue = Boolean.parseBoolean(value);
-            if (value != null) {
-                int intValue = booleanValue.booleanValue() ? 1 : 0;
-                ((BitVector) vector).set(row, intValue);
-            }
+            boolean booleanValue = Boolean.parseBoolean(value);
+            int intValue = booleanValue ? 1 : 0;
+            ((BitVector) vector).set(row, intValue);
             return;
         }
 
@@ -180,7 +179,7 @@ public static void setValue(FieldVector vector, int row, String value) {
             Decimal256Vector decimalVector = (Decimal256Vector) vector;
             int scale = decimalVector.getScale();
             if (decimal.scale() != scale) {
-                decimal = decimal.setScale(scale);
+                decimal = decimal.setScale(scale, RoundingMode.CEILING);
             }
             decimalVector.set(row, decimal);
             return;
@@ -190,7 +189,7 @@ public static void setValue(FieldVector vector, int row, String value) {
     }
 
     public static void setDecimal(DecimalVector vector, int row, String str) {
-        if (str == null || str.length() == 0) {
+        if (str == null || str.isEmpty()) {
             vector.setNull(row);
             return;
         }
@@ -296,7 +295,7 @@ public static void setDecimal(DecimalVector vector, int row, char[] bytes, int o
 
                 BigDecimal decimal = BigDecimal.valueOf(unscaleValue, scale);
                 if (vector.getScale() != decimal.scale()) {
-                    decimal = decimal.setScale(vector.getScale(), BigDecimal.ROUND_CEILING);
+                    decimal = decimal.setScale(vector.getScale(), RoundingMode.CEILING);
                 }
                 vector.set(row, decimal);
                 return;
@@ -305,7 +304,7 @@ public static void setDecimal(DecimalVector vector, int row, char[] bytes, int o
 
         BigDecimal decimal = TypeUtils.parseBigDecimal(bytes, off, len);
         if (vector.getScale() != decimal.scale()) {
-            decimal = decimal.setScale(vector.getScale(), BigDecimal.ROUND_CEILING);
+            decimal = decimal.setScale(vector.getScale(), RoundingMode.CEILING);
         }
         vector.set(row, decimal);
     }
@@ -386,7 +385,7 @@ public static void setDecimal(DecimalVector vector, int row, byte[] bytes, int o
 
                 BigDecimal decimal = BigDecimal.valueOf(unscaleValue, scale);
                 if (vector.getScale() != decimal.scale()) {
-                    decimal = decimal.setScale(vector.getScale(), BigDecimal.ROUND_CEILING);
+                    decimal = decimal.setScale(vector.getScale(), RoundingMode.CEILING);
                 }
                 vector.set(row, decimal);
                 return;
@@ -395,7 +394,7 @@ public static void setDecimal(DecimalVector vector, int row, byte[] bytes, int o
 
         BigDecimal decimal = TypeUtils.parseBigDecimal(bytes, off, len);
         if (vector.getScale() != decimal.scale()) {
-            decimal = decimal.setScale(vector.getScale(), BigDecimal.ROUND_CEILING);
+            decimal = decimal.setScale(vector.getScale(), RoundingMode.CEILING);
         }
         vector.set(row, decimal);
     }
@@ -403,7 +402,7 @@ public static void setDecimal(DecimalVector vector, int row, byte[] bytes, int o
     public static void setDecimal(DecimalVector vector, int row, BigDecimal decimal) {
         int scale = vector.getScale();
         if (decimal.scale() != scale) {
-            decimal = decimal.setScale(scale, BigDecimal.ROUND_CEILING);
+            decimal = decimal.setScale(scale, RoundingMode.CEILING);
         }
         int precision = decimal.precision();
         if (precision < 19 && FIELD_DECIMAL_INT_COMPACT_OFFSET != -1) {
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/arrow/CSVUtils.java b/extension/src/main/java/com/alibaba/fastjson2/support/arrow/CSVUtils.java
index 64c76a00bb..8aa8512d4f 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/arrow/CSVUtils.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/arrow/CSVUtils.java
@@ -22,7 +22,7 @@ public static String genMaxComputeCreateTable(File file, String tableName) throw
 
             String columnName;
             {
-                StringBuffer buf = new StringBuffer();
+                StringBuilder buf = new StringBuilder();
                 for (int j = 0; j < columnStat.name.length(); j++) {
                     char ch = columnStat.name.charAt(j);
                     if (ch == 0xFFFD) {
@@ -62,7 +62,7 @@ public static String genMaxComputeCreateTable(File file, String tableName) throw
             sql.append('\t');
 
             if (special) {
-                sql.append("COL_" + i);
+                sql.append("COL_").append(i);
             } else {
                 sql.append(columnName);
             }
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/geo/Feature.java b/extension/src/main/java/com/alibaba/fastjson2/support/geo/Feature.java
index 8e7618965c..61fd4da7a2 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/geo/Feature.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/geo/Feature.java
@@ -13,7 +13,7 @@ public class Feature
         extends Geometry {
     private String id;
     private Geometry geometry;
-    private Map<String, String> properties = new LinkedHashMap<String, String>();
+    private Map<String, String> properties = new LinkedHashMap<>();
     public Feature() {
         super("Feature");
     }
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/geo/FeatureCollection.java b/extension/src/main/java/com/alibaba/fastjson2/support/geo/FeatureCollection.java
index ce60227073..c184676b47 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/geo/FeatureCollection.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/geo/FeatureCollection.java
@@ -11,7 +11,7 @@
 @JSONType(typeName = "FeatureCollection", orders = {"type", "bbox", "coordinates"})
 public class FeatureCollection
         extends Geometry {
-    private List<Feature> features = new ArrayList<Feature>();
+    private List<Feature> features = new ArrayList<>();
     public FeatureCollection() {
         super("FeatureCollection");
     }
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/geo/GeometryCollection.java b/extension/src/main/java/com/alibaba/fastjson2/support/geo/GeometryCollection.java
index a3e5c95b75..43c4832c43 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/geo/GeometryCollection.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/geo/GeometryCollection.java
@@ -11,7 +11,7 @@
 @JSONType(typeName = "GeometryCollection", orders = {"type", "bbox", "geometries"})
 public class GeometryCollection
         extends Geometry {
-    private List<Geometry> geometries = new ArrayList<Geometry>();
+    private List<Geometry> geometries = new ArrayList<>();
     public GeometryCollection() {
         super("GeometryCollection");
     }
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/redission/JSONBCodec.java b/extension/src/main/java/com/alibaba/fastjson2/support/redission/JSONBCodec.java
index 81d5239412..59601011ef 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/redission/JSONBCodec.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/redission/JSONBCodec.java
@@ -99,7 +99,7 @@ public ByteBuf encode(Object object) throws IOException {
         }
     }
 
-    static final class JSONBDecoder
+    protected static final class JSONBDecoder
             implements Decoder<Object> {
         final JSONReader.Context context;
         final Type valueType;
diff --git a/extension/src/main/java/com/alibaba/fastjson2/support/retrofit/Retrofit2ConverterFactory.java b/extension/src/main/java/com/alibaba/fastjson2/support/retrofit/Retrofit2ConverterFactory.java
index 471a88402f..1272ec2dd0 100644
--- a/extension/src/main/java/com/alibaba/fastjson2/support/retrofit/Retrofit2ConverterFactory.java
+++ b/extension/src/main/java/com/alibaba/fastjson2/support/retrofit/Retrofit2ConverterFactory.java
@@ -52,7 +52,7 @@ public Converter<ResponseBody, Object> responseBodyConverter(
             Annotation[] annotations,
             Retrofit retrofit
     ) {
-        return new ResponseBodyConverter<Object>(type);
+        return new ResponseBodyConverter<>(type);
     }
 
     @Override
@@ -62,7 +62,7 @@ public Converter<Object, RequestBody> requestBodyConverter(
             Annotation[] methodAnnotations,
             Retrofit retrofit
     ) {
-        return new RequestBodyConverter<Object>();
+        return new RequestBodyConverter<>();
     }
 
     public FastJsonConfig getFastJsonConfig() {
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSON.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSON.java
index 105fc64be2..a02a507e88 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSON.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSON.java
@@ -9,7 +9,6 @@
 import com.alibaba.fastjson2.JSONFactory;
 import com.alibaba.fastjson2.JSONReader;
 import com.alibaba.fastjson2.JSONWriter;
-import com.alibaba.fastjson2.filter.Filter;
 import com.alibaba.fastjson2.filter.PropertyFilter;
 import com.alibaba.fastjson2.filter.PropertyPreFilter;
 import com.alibaba.fastjson2.filter.ValueFilter;
@@ -514,14 +513,13 @@ public static <T> T parseObject(String str, Class<T> objectClass, ParseProcess p
         }
     }
 
-    @SuppressWarnings("unchecked")
     public static <T> T parseObject(String str, TypeReference<T> typeReference, Feature... features) {
         Type type = typeReference != null ? typeReference.getType() : Object.class;
-        return (T) parseObject(str, type, features);
+        return parseObject(str, type, features);
     }
 
     public static <T> T parseObject(String input, Type clazz, int featureValues, Feature... features) {
-        return (T) parseObject(input, clazz, ParserConfig.global, featureValues, features);
+        return parseObject(input, clazz, ParserConfig.global, featureValues, features);
     }
 
     public static <T> T parseObject(String str, Class<T> objectClass) {
@@ -723,7 +721,7 @@ public static <T> T parseObject(
             ParserConfig config,
             Feature... features
     ) throws IOException {
-        return (T) parseObject(is, charset, type, config, null, DEFAULT_PARSER_FEATURE, features);
+        return parseObject(is, charset, type, config, null, DEFAULT_PARSER_FEATURE, features);
     }
 
     public static <T> T parseObject(
@@ -763,7 +761,7 @@ public static <T> T parseObject(
     /**
      * @since 2.0.7
      */
-    public static <T> JSONObject parseObject(byte[] jsonBytes, Feature... features) {
+    public static JSONObject parseObject(byte[] jsonBytes, Feature... features) {
         if (jsonBytes == null || jsonBytes.length == 0) {
             return null;
         }
@@ -896,8 +894,8 @@ public static <T> T parseObject(byte[] jsonBytes, Type type, SerializeFilter fil
         try {
             JSONReader jsonReader = JSONReader.of(jsonBytes, context);
 
-            if (filter instanceof Filter) {
-                context.config((Filter) filter);
+            if (filter != null) {
+                context.config(filter);
             }
 
             ObjectReader<T> objectReader = jsonReader.getObjectReader(type);
@@ -1134,7 +1132,6 @@ public static Object parse(byte[] input, int off, int len, CharsetDecoder charse
         }
     }
 
-    @SuppressWarnings("unchecked")
     public static <T> T parseObject(
             byte[] input,
             int off,
@@ -1608,7 +1605,7 @@ public static byte[] toJSONBytes(Object object, SerializeConfig config, Serializ
     public static String toJSONString(Object object, boolean prettyFormat) {
         SerializerFeature[] features = prettyFormat
                 ? new SerializerFeature[]{SerializerFeature.PrettyFormat}
-                : new SerializerFeature[0];
+                : SerializerFeature.EMPTY;
         JSONWriter.Context context =
                 createWriteContext(SerializeConfig.global, DEFAULT_GENERATE_FEATURE, features);
 
@@ -1726,7 +1723,7 @@ public static byte[] toJSONBytes(Object object) {
     }
 
     public static byte[] toJSONBytes(Object object, SerializeFilter... filters) {
-        return toJSONBytes(object, filters, new SerializerFeature[0]);
+        return toJSONBytes(object, filters, SerializerFeature.EMPTY);
     }
 
     public static byte[] toJSONBytes(Object object, int defaultFeatures, SerializerFeature... features) {
@@ -1945,7 +1942,7 @@ public static final int writeJSONString(
             OutputStream os,
             Object object,
             SerializeFilter[] filters) throws IOException {
-        return writeJSONString(os, object, filters, new SerializerFeature[0]);
+        return writeJSONString(os, object, filters, SerializerFeature.EMPTY);
     }
 
     public static final int writeJSONString(
@@ -2295,7 +2292,7 @@ public <T> T toJavaObject(TypeReference<T> typeReference) {
 
     public static <T> T toJavaObject(JSON json, Class<T> clazz) {
         if (json instanceof JSONObject) {
-            return ((JSONObject) json).toJavaObject(clazz);
+            return json.toJavaObject(clazz);
         }
 
         String str = toJSONString(json);
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONArray.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONArray.java
index e9ee4fe012..a9eed4ead1 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONArray.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONArray.java
@@ -192,12 +192,12 @@ public BigDecimal getBigDecimal(int index) {
             }
 
             if (value instanceof Float) {
-                float floatValue = ((Float) value).floatValue();
+                float floatValue = (Float) value;
                 return toBigDecimal(floatValue);
             }
 
             if (value instanceof Double) {
-                double doubleValue = ((Double) value).doubleValue();
+                double doubleValue = (Double) value;
                 return toBigDecimal(doubleValue);
             }
 
@@ -821,7 +821,7 @@ public <T> T getObject(int index, Type type) {
             return (T) TypeUtils.cast(obj, (Class) type);
         } else {
             String json = JSON.toJSONString(obj);
-            return (T) JSON.parseObject(json, type);
+            return JSON.parseObject(json, type);
         }
     }
 
@@ -856,7 +856,7 @@ public <T> T getObject(int index, Class<T> clazz) {
     }
 
     public <T> List<T> toJavaList(Class<T> clazz) {
-        List<T> list = new ArrayList<T>(this.size());
+        List<T> list = new ArrayList<>(this.size());
 
         ObjectReaderProvider provider = JSONFactory.getDefaultObjectReaderProvider();
         ObjectReader objectReader = provider.getObjectReader(clazz);
@@ -877,10 +877,8 @@ public <T> List<T> toJavaList(Class<T> clazz) {
                     list.add((T) converted);
                     continue;
                 }
-
-                throw new com.alibaba.fastjson2.JSONException(
-                        (item == null ? "null" : item.getClass()) + " cannot be converted to " + clazz
-                );
+                // item is NOT null here
+                throw new com.alibaba.fastjson2.JSONException(item.getClass() + " cannot be converted to " + clazz);
             }
             list.add(classItem);
         }
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONObject.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONObject.java
index 2bcf308a92..bd0b7ceb99 100755
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONObject.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONObject.java
@@ -78,9 +78,9 @@ public JSONObject(int initialCapacity) {
 
     public JSONObject(int initialCapacity, boolean ordered) {
         if (ordered) {
-            map = new LinkedHashMap<String, Object>(initialCapacity);
+            map = new LinkedHashMap<>(initialCapacity);
         } else {
-            map = new HashMap<String, Object>(initialCapacity);
+            map = new HashMap<>(initialCapacity);
         }
     }
 
@@ -425,7 +425,7 @@ public boolean getBooleanValue(String key) {
             return false;
         }
 
-        return booleanVal.booleanValue();
+        return booleanVal;
     }
 
     public byte getByteValue(String key) {
@@ -751,12 +751,12 @@ public BigDecimal getBigDecimal(String key) {
             }
 
             if (value instanceof Float) {
-                float floatValue = ((Float) value).floatValue();
+                float floatValue = (Float) value;
                 return toBigDecimal(floatValue);
             }
 
             if (value instanceof Double) {
-                double doubleValue = ((Double) value).doubleValue();
+                double doubleValue = (Double) value;
                 return toBigDecimal(doubleValue);
             }
 
@@ -856,11 +856,11 @@ public JSONObject fluentPut(String key, Object value) {
     }
 
     @Override
-    public void putAll(Map<? extends String, ? extends Object> m) {
+    public void putAll(Map<? extends String, ?> m) {
         map.putAll(m);
     }
 
-    public JSONObject fluentPutAll(Map<? extends String, ? extends Object> m) {
+    public JSONObject fluentPutAll(Map<? extends String, ?> m) {
         map.putAll(m);
         return this;
     }
@@ -903,8 +903,8 @@ public Set<Entry<String, Object>> entrySet() {
     @Override
     public Object clone() {
         return new JSONObject(map instanceof LinkedHashMap //
-                ? new LinkedHashMap<String, Object>(map) //
-                : new HashMap<String, Object>(map)
+                ? new LinkedHashMap<>(map) //
+                : new HashMap<>(map)
         );
     }
 
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPObject.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPObject.java
index f3d8765af3..9a27f3c5ec 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPObject.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPObject.java
@@ -5,7 +5,7 @@
 
 public class JSONPObject
         extends com.alibaba.fastjson2.JSONPObject {
-    private final List<Object> parameters = new ArrayList<Object>();
+    private final List<Object> parameters = new ArrayList<>();
 
     public JSONPObject() {
     }
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPath.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPath.java
index 20a8958c6a..2908bb4bf0 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPath.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/JSONPath.java
@@ -51,21 +51,20 @@ public static <T> T read(String json, String path, Type clazz) {
 
     public static Object eval(String rootObject, String path) {
         Object result = com.alibaba.fastjson2.JSONPath.eval(rootObject, path);
-        if (result instanceof com.alibaba.fastjson2.JSONArray) {
-            result = new com.alibaba.fastjson.JSONArray((com.alibaba.fastjson2.JSONArray) result);
-        } else if (result instanceof com.alibaba.fastjson2.JSONObject) {
-            result = new com.alibaba.fastjson.JSONObject((com.alibaba.fastjson2.JSONObject) result);
-        }
-        return result;
+        return adaptResult(result);
     }
 
     public static Object eval(Object rootObject, String path) {
         com.alibaba.fastjson2.JSONPath jsonPath = com.alibaba.fastjson2.JSONPath.of(path);
         Object result = jsonPath.eval(rootObject);
+        return adaptResult(result);
+    }
+
+    private static Object adaptResult(Object result) {
         if (result instanceof com.alibaba.fastjson2.JSONArray) {
-            result = new com.alibaba.fastjson.JSONArray((com.alibaba.fastjson2.JSONArray) result);
+            result = new JSONArray((com.alibaba.fastjson2.JSONArray) result);
         } else if (result instanceof com.alibaba.fastjson2.JSONObject) {
-            result = new com.alibaba.fastjson.JSONObject((com.alibaba.fastjson2.JSONObject) result);
+            result = new JSONObject((com.alibaba.fastjson2.JSONObject) result);
         }
         return result;
     }
@@ -91,12 +90,7 @@ public static Object extract(String json, String path) {
         JSONReader.Context context = JSON.createReadContext(JSON.DEFAULT_PARSER_FEATURE);
         JSONReader jsonReader = JSONReader.of(json, context);
         Object result = jsonPath.extract(jsonReader);
-        if (result instanceof com.alibaba.fastjson2.JSONArray) {
-            result = new com.alibaba.fastjson.JSONArray((com.alibaba.fastjson2.JSONArray) result);
-        } else if (result instanceof com.alibaba.fastjson2.JSONObject) {
-            result = new com.alibaba.fastjson.JSONObject((com.alibaba.fastjson2.JSONObject) result);
-        }
-        return result;
+        return adaptResult(result);
     }
 
     public static boolean remove(Object root, String path) {
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/TypeReference.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/TypeReference.java
index 9fe770a835..bf9a24b114 100755
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/TypeReference.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/TypeReference.java
@@ -27,7 +27,7 @@
  */
 public class TypeReference<T> {
     static ConcurrentMap<Type, Type> classTypeCache
-            = new ConcurrentHashMap<Type, Type>(16, 0.75f, 1);
+            = new ConcurrentHashMap<>(16, 0.75f, 1);
 
     protected final Type type;
 
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/jaxrs/FastJsonProvider.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/jaxrs/FastJsonProvider.java
index 8ae5de1e99..492048c9b9 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/jaxrs/FastJsonProvider.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/jaxrs/FastJsonProvider.java
@@ -17,6 +17,7 @@
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Type;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -55,10 +56,10 @@ public class FastJsonProvider
     };
 
     @Deprecated
-    protected Charset charset = Charset.forName("UTF-8");
+    protected Charset charset = StandardCharsets.UTF_8;
 
     @Deprecated
-    protected SerializerFeature[] features = new SerializerFeature[0];
+    protected SerializerFeature[] features = SerializerFeature.EMPTY;
 
     @Deprecated
     protected SerializeFilter[] filters = new SerializeFilter[0];
@@ -358,7 +359,7 @@ public void writeTo(
             if (serializerFeatures == null) {
                 serializerFeatures = new SerializerFeature[]{SerializerFeature.PrettyFormat};
             } else {
-                List<SerializerFeature> featureList = new ArrayList<SerializerFeature>(Arrays.asList(serializerFeatures));
+                List<SerializerFeature> featureList = new ArrayList<>(Arrays.asList(serializerFeatures));
                 featureList.add(SerializerFeature.PrettyFormat);
                 serializerFeatures = featureList.toArray(serializerFeatures);
             }
@@ -397,10 +398,8 @@ static final int writeJSONStringWithFastJsonConfig(
         }
 
         JSONWriter.Context context = JSON.createWriteContext(config, defaultFeatures, features);
-        com.alibaba.fastjson2.JSONWriter writer = com.alibaba.fastjson2.JSONWriter.ofUTF8(context);
         context.setDateFormat(dateFormat);
-
-        try {
+        try (JSONWriter writer = JSONWriter.ofUTF8(context)) {
             if (filters != null) {
                 for (SerializeFilter filter : filters) {
                     JSON.configFilter(context, filter);
@@ -409,10 +408,7 @@ static final int writeJSONStringWithFastJsonConfig(
 
             writer.writeAny(object);
 
-            int len = writer.flushTo(os, charset);
-            return len;
-        } finally {
-            writer.close();
+            return writer.flushTo(os, charset);
         }
     }
 
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/FastJsonJsonView.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/FastJsonJsonView.java
index a699c3df10..089afca69d 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/FastJsonJsonView.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/FastJsonJsonView.java
@@ -17,6 +17,7 @@
 
 import java.io.ByteArrayOutputStream;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
@@ -48,10 +49,10 @@ public class FastJsonJsonView
     private static final Pattern CALLBACK_PARAM_PATTERN = Pattern.compile("[0-9A-Za-z_\\.]*");
 
     @Deprecated
-    protected Charset charset = Charset.forName("UTF-8");
+    protected Charset charset = StandardCharsets.UTF_8;
 
     @Deprecated
-    protected SerializerFeature[] features = new SerializerFeature[0];
+    protected SerializerFeature[] features = SerializerFeature.EMPTY;
 
     @Deprecated
     protected SerializeFilter[] filters = new SerializeFilter[0];
@@ -359,7 +360,7 @@ public void setUpdateContentLength(boolean updateContentLength) {
      * @return the object to be rendered
      */
     protected Object filterModel(Map<String, Object> model) {
-        Map<String, Object> result = new HashMap<String, Object>(model.size());
+        Map<String, Object> result = new HashMap<>(model.size());
         Set<String> renderedAttributes = !CollectionUtils.isEmpty(this.renderedAttributes) ? //
                 this.renderedAttributes //
                 : model.keySet();
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/PropertyPreFilters.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/PropertyPreFilters.java
index 7971b812e5..5cbb918a60 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/PropertyPreFilters.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/PropertyPreFilters.java
@@ -12,7 +12,7 @@
  * @author liuming
  */
 public class PropertyPreFilters {
-    private List<MySimplePropertyPreFilter> filters = new ArrayList<MySimplePropertyPreFilter>();
+    private List<MySimplePropertyPreFilter> filters = new ArrayList<>();
 
     public MySimplePropertyPreFilter addFilter() {
         MySimplePropertyPreFilter filter = new MySimplePropertyPreFilter();
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/annotation/FastJsonView.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/annotation/FastJsonView.java
index 209a776974..d1465abf88 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/annotation/FastJsonView.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/support/spring/annotation/FastJsonView.java
@@ -163,7 +163,7 @@ public void setUpdateContentLength(boolean updateContentLength) {
      * @return the object to be rendered
      */
     protected Object filterModel(Map<String, Object> model) {
-        Map<String, Object> result = new HashMap<String, Object>(model.size());
+        Map<String, Object> result = new HashMap<>(model.size());
         Set<String> renderedAttributes = !CollectionUtils.isEmpty(this.renderedAttributes) ? //
                 this.renderedAttributes //
                 : model.keySet();
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/FieldInfo.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/FieldInfo.java
index e9ad13214e..ab666fb221 100644
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/FieldInfo.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/FieldInfo.java
@@ -110,11 +110,11 @@ public FieldInfo(
 
         nameHashCode = nameHashCode64(name, annotation);
 
-        boolean jsonDirect = false;
+        boolean jsonDirect;
         if (annotation != null) {
             format = annotation.format();
 
-            if (format.trim().length() == 0) {
+            if (format.trim().isEmpty()) {
                 format = null;
             }
             jsonDirect = annotation.jsonDirect();
@@ -288,7 +288,7 @@ public static Type getFieldType(
     }
 
     private static boolean getArgument(Type[] typeArgs, Map<TypeVariable, Type> genericInfo) {
-        if (genericInfo == null || genericInfo.size() == 0) {
+        if (genericInfo == null || genericInfo.isEmpty()) {
             return false;
         }
         boolean changed = false;
@@ -305,8 +305,9 @@ private static boolean getArgument(Type[] typeArgs, Map<TypeVariable, Type> gene
                     changed = true;
                 }
             } else if (typeArg instanceof TypeVariable) {
-                if (genericInfo.containsKey(typeArg)) {
-                    typeArgs[i] = genericInfo.get(typeArg);
+                Type type = genericInfo.get(typeArg);
+                if (type != null) { // genericInfo should NOT contain null value
+                    typeArgs[i] = type;
                     changed = true;
                 }
             }
diff --git a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/TypeUtils.java b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/TypeUtils.java
index e79942c9a4..5762796d8f 100755
--- a/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/TypeUtils.java
+++ b/fastjson1-compatible/src/main/java/com/alibaba/fastjson/util/TypeUtils.java
@@ -35,8 +35,6 @@
 import java.math.BigInteger;
 import java.sql.Timestamp;
 import java.util.*;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.ConcurrentMap;
 
 /**
  * @author wenshao[szujobs@hotmail.com]
@@ -59,14 +57,10 @@ public class TypeUtils {
     private static volatile boolean kotlin_error;
     private static volatile Map<Class, String[]> kotlinIgnores;
     private static volatile boolean kotlinIgnores_error;
-    private static ConcurrentMap<String, Class<?>> mappings = new ConcurrentHashMap<String, Class<?>>(256, 0.75f, 1);
-    private static Class<?> pathClass;
-    private static boolean PATH_CLASS_ERROR;
 
     private static boolean transientClassInited;
     private static Class<? extends Annotation> transientClass;
 
-    @SuppressWarnings({"unchecked", "rawtypes"})
     public static <T> T cast(Object obj, Class<T> clazz, ParserConfig config) {
         return com.alibaba.fastjson2.util.TypeUtils.cast(obj, clazz, config.getProvider());
     }
@@ -102,72 +96,42 @@ public static <T> T cast(Object obj, Type type, ParserConfig mapping) {
 
     @SuppressWarnings({"rawtypes", "unchecked"})
     public static <T> T cast(Object obj, ParameterizedType type, ParserConfig mapping) {
-        Type rawTye = type.getRawType();
+        final Type rawType = type.getRawType();
 
-        if (rawTye == List.class || rawTye == ArrayList.class) {
+        if (rawType == List.class || rawType == ArrayList.class) {
             Type itemType = type.getActualTypeArguments()[0];
             if (obj instanceof List) {
                 List listObj = (List) obj;
                 List arrayList = new ArrayList(listObj.size());
 
-                for (int i = 0; i < listObj.size(); i++) {
-                    Object item = listObj.get(i);
-
-                    Object itemValue;
-                    if (itemType instanceof Class) {
-                        if (item != null && item.getClass() == JSONObject.class) {
-                            itemValue = ((JSONObject) item).toJavaObject((Class<T>) itemType, mapping, 0);
-                        } else {
-                            itemValue = cast(item, (Class<T>) itemType, mapping);
-                        }
-                    } else {
-                        itemValue = cast(item, itemType, mapping);
-                    }
-
-                    arrayList.add(itemValue);
-                }
+                castItemsTo(mapping, listObj, itemType, arrayList);
                 return (T) arrayList;
             }
         }
 
-        if (rawTye == Set.class || rawTye == HashSet.class //
-                || rawTye == TreeSet.class //
-                || rawTye == Collection.class //
-                || rawTye == List.class //
-                || rawTye == ArrayList.class) {
+        if (rawType == Set.class || rawType == HashSet.class //
+                || rawType == TreeSet.class //
+                || rawType == Collection.class //
+                || rawType == List.class //
+                || rawType == ArrayList.class) {
             Type itemType = type.getActualTypeArguments()[0];
             if (obj instanceof Iterable) {
                 Collection collection;
-                if (rawTye == Set.class || rawTye == HashSet.class) {
+                if (rawType == Set.class || rawType == HashSet.class) {
                     collection = new HashSet();
-                } else if (rawTye == TreeSet.class) {
+                } else if (rawType == TreeSet.class) {
                     collection = new TreeSet();
                 } else {
                     collection = new ArrayList();
                 }
-                for (Iterator it = ((Iterable) obj).iterator(); it.hasNext(); ) {
-                    Object item = it.next();
-
-                    Object itemValue;
-                    if (itemType instanceof Class) {
-                        if (item != null && item.getClass() == JSONObject.class) {
-                            itemValue = ((JSONObject) item).toJavaObject((Class<T>) itemType, mapping, 0);
-                        } else {
-                            itemValue = cast(item, (Class<T>) itemType, mapping);
-                        }
-                    } else {
-                        itemValue = cast(item, itemType, mapping);
-                    }
-
-                    collection.add(itemValue);
-                }
+                castItemsTo(mapping, (Iterable) obj, itemType, collection);
                 return (T) collection;
             }
         }
 
-        if (rawTye == Map.class || rawTye == HashMap.class) {
-            Type keyType = type.getActualTypeArguments()[0];
-            Type valueType = type.getActualTypeArguments()[1];
+        if (rawType == Map.class || rawType == HashMap.class) {
+            final Type[] args = type.getActualTypeArguments();
+            Type keyType = args[0], valueType = args[1];
             if (obj instanceof Map) {
                 Map map = new HashMap();
                 for (Map.Entry entry : ((Map<?, ?>) obj).entrySet()) {
@@ -180,23 +144,24 @@ public static <T> T cast(Object obj, ParameterizedType type, ParserConfig mappin
         }
         if (obj instanceof String) {
             String strVal = (String) obj;
-            if (strVal.length() == 0) {
+            if (strVal.isEmpty()) {
                 return null;
             }
         }
-        if (type.getActualTypeArguments().length == 1) {
-            Type argType = type.getActualTypeArguments()[0];
+        final Type[] args = type.getActualTypeArguments();
+        if (args.length == 1) {
+            Type argType = args[0];
             if (argType instanceof WildcardType) {
-                return cast(obj, rawTye, mapping);
+                return cast(obj, rawType, mapping);
             }
         }
 
-        if (rawTye == Map.Entry.class && obj instanceof Map && ((Map) obj).size() == 1) {
+        if (rawType == Map.Entry.class && obj instanceof Map && ((Map) obj).size() == 1) {
             Map.Entry entry = (Map.Entry) ((Map) obj).entrySet().iterator().next();
             return (T) entry;
         }
 
-        if (rawTye instanceof Class) {
+        if (rawType instanceof Class) {
             if (mapping == null) {
                 mapping = ParserConfig.global;
             }
@@ -207,12 +172,29 @@ public static <T> T cast(Object obj, ParameterizedType type, ParserConfig mappin
 //                return (T) deserializer.deserialze(parser, type, null);
 //            }
 
-            throw new JSONException("TODO : " + type); // TOD: cast
+            throw new JSONException("TODO : " + type); // TODO: cast
         }
 
         throw new JSONException("can not cast to : " + type);
     }
 
+    private static <T> void castItemsTo(ParserConfig mapping, Iterable items, Type itemType, Collection to) {
+        for (Object item : items) {
+            Object itemValue;
+            if (itemType instanceof Class) {
+                if (item != null && item.getClass() == JSONObject.class) {
+                    itemValue = ((JSONObject) item).toJavaObject((Class<T>) itemType, mapping, 0);
+                } else {
+                    itemValue = cast(item, (Class<T>) itemType, mapping);
+                }
+            } else {
+                itemValue = cast(item, itemType, mapping);
+            }
+
+            to.add(itemValue);
+        }
+    }
+
     @SuppressWarnings("unchecked")
     public static <T> T castToJavaBean(Map<String, Object> map, Class<T> clazz, ParserConfig config) {
         try {
@@ -297,8 +279,8 @@ public static <T> T castToJavaBean(Map<String, Object> map, Class<T> clazz, Pars
                 if (innerMap instanceof LinkedHashMap) {
                     return (T) innerMap;
                 } else {
-                    LinkedHashMap linkedHashMap = new LinkedHashMap();
-                    linkedHashMap.putAll(innerMap);
+                    // 这里应该返回 LinkedHashMap
+                    return (T) new LinkedHashMap(innerMap);
                 }
             }
 
@@ -465,52 +447,36 @@ public static long longExtractValue(Number number) {
     }
 
     public static <A extends Annotation> A getAnnotation(Class<?> targetClass, Class<A> annotationClass) {
-        A targetAnnotation = targetClass.getAnnotation(annotationClass);
-
-        Class<?> mixInClass = null;
-        Type type = JSON.getMixInAnnotations(targetClass);
-        if (type instanceof Class<?>) {
-            mixInClass = (Class<?>) type;
-        }
+        Class<?> mixInClass = getMixInClass(targetClass);
 
         if (mixInClass != null) {
-            A mixInAnnotation = mixInClass.getAnnotation(annotationClass);
-            Annotation[] annotations = mixInClass.getAnnotations();
-            if (mixInAnnotation == null && annotations.length > 0) {
-                for (Annotation annotation : annotations) {
-                    mixInAnnotation = annotation.annotationType().getAnnotation(annotationClass);
-                    if (mixInAnnotation != null) {
-                        break;
-                    }
-                }
-            }
+            A mixInAnnotation = getAnnotationOrCandidate(mixInClass, annotationClass);
             if (mixInAnnotation != null) {
                 return mixInAnnotation;
             }
         }
 
-        Annotation[] targetClassAnnotations = targetClass.getAnnotations();
-        if (targetAnnotation == null && targetClassAnnotations.length > 0) {
-            for (Annotation annotation : targetClassAnnotations) {
-                targetAnnotation = annotation.annotationType().getAnnotation(annotationClass);
-                if (targetAnnotation != null) {
+        return getAnnotationOrCandidate(targetClass, annotationClass);
+    }
+
+    private static <A extends Annotation> A getAnnotationOrCandidate(Class<?> clazz, Class<A> annotationClass) {
+        A target = clazz.getAnnotation(annotationClass);
+        if (target == null) {
+            Annotation[] candidates = clazz.getAnnotations();
+            for (Annotation annotation : candidates) {
+                target = annotation.annotationType().getAnnotation(annotationClass);
+                if (target != null) {
                     break;
                 }
             }
         }
-        return targetAnnotation;
+        return target;
     }
 
     public static <A extends Annotation> A getAnnotation(Field field, Class<A> annotationClass) {
         A targetAnnotation = field.getAnnotation(annotationClass);
 
-        Class<?> clazz = field.getDeclaringClass();
-        A mixInAnnotation;
-        Class<?> mixInClass = null;
-        Type type = JSON.getMixInAnnotations(clazz);
-        if (type instanceof Class<?>) {
-            mixInClass = (Class<?>) type;
-        }
+        Class<?> mixInClass = getMixInClass(field.getDeclaringClass());
 
         if (mixInClass != null) {
             Field mixInField = null;
@@ -527,7 +493,7 @@ public static <A extends Annotation> A getAnnotation(Field field, Class<A> annot
             if (mixInField == null) {
                 return targetAnnotation;
             }
-            mixInAnnotation = mixInField.getAnnotation(annotationClass);
+            A mixInAnnotation = mixInField.getAnnotation(annotationClass);
             if (mixInAnnotation != null) {
                 return mixInAnnotation;
             }
@@ -535,16 +501,17 @@ public static <A extends Annotation> A getAnnotation(Field field, Class<A> annot
         return targetAnnotation;
     }
 
-    public static <A extends Annotation> A getAnnotation(Method method, Class<A> annotationClass) {
-        A targetAnnotation = method.getAnnotation(annotationClass);
-
-        Class<?> clazz = method.getDeclaringClass();
-        A mixInAnnotation;
-        Class<?> mixInClass = null;
+    private static Class<?> getMixInClass(Class<?> clazz) {
         Type type = JSON.getMixInAnnotations(clazz);
+        Class<?> mixInClass = null;
         if (type instanceof Class<?>) {
             mixInClass = (Class<?>) type;
         }
+        return mixInClass;
+    }
+
+    public static <A extends Annotation> A getAnnotation(Method method, Class<A> annotationClass) {
+        Class<?> mixInClass = getMixInClass(method.getDeclaringClass());
 
         if (mixInClass != null) {
             Method mixInMethod = null;
@@ -559,15 +526,14 @@ public static <A extends Annotation> A getAnnotation(Method method, Class<A> ann
                     // skip
                 }
             }
-            if (mixInMethod == null) {
-                return targetAnnotation;
-            }
-            mixInAnnotation = mixInMethod.getAnnotation(annotationClass);
-            if (mixInAnnotation != null) {
-                return mixInAnnotation;
+            if (mixInMethod != null) {
+                A mixInAnnotation = mixInMethod.getAnnotation(annotationClass);
+                if (mixInAnnotation != null) {
+                    return mixInAnnotation;
+                }
             }
         }
-        return targetAnnotation;
+        return method.getAnnotation(annotationClass);
     }
 
     public static Double castToDouble(Object value) {
@@ -715,7 +681,7 @@ public static List<FieldInfo> computeGetters(Class<?> clazz, Map<String, String>
 
     public static List<FieldInfo> computeGetters(Class<?> clazz, Map<String, String> aliasMap, boolean sorted) {
         JSONType jsonType = TypeUtils.getAnnotation(clazz, JSONType.class);
-        Map<String, Field> fieldCacheMap = new HashMap<String, Field>();
+        Map<String, Field> fieldCacheMap = new HashMap<>();
         ParserConfig.parserAllFieldToCache(clazz, fieldCacheMap);
         return computeGetters(clazz, jsonType, aliasMap, fieldCacheMap, sorted, PropertyNamingStrategy.CamelCase);
     }
@@ -727,7 +693,7 @@ public static List<FieldInfo> computeGetters(Class<?> clazz, //
                                                  boolean sorted, //
                                                  PropertyNamingStrategy propertyNamingStrategy //
     ) {
-        Map<String, FieldInfo> fieldInfoMap = new LinkedHashMap<String, FieldInfo>();
+        Map<String, FieldInfo> fieldInfoMap = new LinkedHashMap<>();
         boolean kotlin = TypeUtils.isKotlin(clazz);
         // for kotlin
         Constructor[] constructors = null;
@@ -776,10 +742,10 @@ public static List<FieldInfo> computeGetters(Class<?> clazz, //
             if (kotlin && isKotlinIgnore(clazz, methodName)) {
                 continue;
             }
-            /**
+            /*
              *  如果在属性或者方法上存在JSONField注解，并且定制了name属性，不以类上的propertyNamingStrategy设置为准，以此字段的JSONField的name定制为准。
              */
-            Boolean fieldAnnotationAndNameExists = false;
+            boolean fieldAnnotationAndNameExists = false;
             JSONField annotation = TypeUtils.getAnnotation(method, JSONField.class);
             if (annotation == null) {
                 annotation = getSuperMethodAnnotation(clazz, method);
@@ -1114,14 +1080,14 @@ private static void computeFields(
     }
 
     private static List<FieldInfo> getFieldInfos(Class<?> clazz, boolean sorted, Map<String, FieldInfo> fieldInfoMap) {
-        List<FieldInfo> fieldInfoList = new ArrayList<FieldInfo>();
+        List<FieldInfo> fieldInfoList = new ArrayList<>();
         String[] orders = null;
         JSONType annotation = TypeUtils.getAnnotation(clazz, JSONType.class);
         if (annotation != null) {
             orders = annotation.orders();
         }
         if (orders != null && orders.length > 0) {
-            LinkedHashMap<String, FieldInfo> map = new LinkedHashMap<String, FieldInfo>(fieldInfoMap.size());
+            LinkedHashMap<String, FieldInfo> map = new LinkedHashMap<>(fieldInfoMap.size());
             for (FieldInfo field : fieldInfoMap.values()) {
                 map.put(field.name, field);
             }
@@ -1178,8 +1144,8 @@ public static Constructor getKotlinConstructor(Constructor[] constructors, Strin
             if (paramNames != null && parameterTypes.length != paramNames.length) {
                 continue;
             }
-
-            if (parameterTypes.length > 0 && "kotlin.jvm.internal.DefaultConstructorMarker".equals(parameterTypes[parameterTypes.length - 1])) {
+            // String equals to Class will always return false !
+            if (parameterTypes.length > 0 && "kotlin.jvm.internal.DefaultConstructorMarker".equals(parameterTypes[parameterTypes.length - 1].getName())) {
                 continue;
             }
             if (creatorConstructor != null && creatorConstructor.getParameterTypes().length >= parameterTypes.length) {
@@ -1238,7 +1204,7 @@ public static String[] getKoltinConstructorParameters(Class clazz) {
             Object constructor = null;
             Object kclassImpl = kotlin_kclass_constructor.newInstance(clazz);
             Iterable it = (Iterable) kotlin_kclass_getConstructors.invoke(kclassImpl);
-            for (Iterator iterator = it.iterator(); iterator.hasNext(); iterator.hasNext()) {
+            for (Iterator iterator = it.iterator(); iterator.hasNext();) {
                 Object item = iterator.next();
                 List parameters = (List) kotlin_kfunction_getParameters.invoke(item);
                 if (constructor != null && parameters.size() == 0) {
@@ -1268,7 +1234,7 @@ public static String[] getKoltinConstructorParameters(Class clazz) {
     static boolean isKotlinIgnore(Class clazz, String methodName) {
         if (kotlinIgnores == null && !kotlinIgnores_error) {
             try {
-                Map<Class, String[]> map = new HashMap<Class, String[]>();
+                Map<Class, String[]> map = new HashMap<>();
                 Class charRangeClass = Class.forName("kotlin.ranges.CharRange");
                 map.put(charRangeClass, new String[]{"getEndInclusive", "isEmpty"});
                 Class intRangeClass = Class.forName("kotlin.ranges.IntRange");
@@ -1417,21 +1383,15 @@ public static String getPropertyNameByMethodName(String methodName) {
     }
 
     public static Annotation[][] getParameterAnnotations(Constructor constructor) {
-        Annotation[][] targetAnnotations = constructor.getParameterAnnotations();
-
         Class<?> clazz = constructor.getDeclaringClass();
-        Annotation[][] mixInAnnotations;
-        Class<?> mixInClass = null;
-        Type type = JSON.getMixInAnnotations(clazz);
-        if (type instanceof Class<?>) {
-            mixInClass = (Class<?>) type;
-        }
+
+        Class<?> mixInClass = getMixInClass(clazz);
 
         if (mixInClass != null) {
             Constructor mixInConstructor = null;
             Class<?>[] parameterTypes = constructor.getParameterTypes();
             // 构建参数列表，因为内部类的构造函数需要传入外部类的引用
-            List<Class<?>> enclosingClasses = new ArrayList<Class<?>>(2);
+            List<Class<?>> enclosingClasses = new ArrayList<>(2);
             for (Class<?> enclosingClass = mixInClass.getEnclosingClass(); enclosingClass != null; enclosingClass = enclosingClass.getEnclosingClass()) {
                 enclosingClasses.add(enclosingClass);
             }
@@ -1454,15 +1414,15 @@ public static Annotation[][] getParameterAnnotations(Constructor constructor) {
                     level--;
                 }
             }
-            if (mixInConstructor == null) {
-                return targetAnnotations;
-            }
-            mixInAnnotations = mixInConstructor.getParameterAnnotations();
-            if (mixInAnnotations != null) {
-                return mixInAnnotations;
+            if (mixInConstructor != null) {
+                // mixInAnnotations is non-null, but length may be 0
+                Annotation[][] mixInAnnotations = mixInConstructor.getParameterAnnotations();
+                if (mixInAnnotations.length == 0) {
+                    return mixInAnnotations;
+                }
             }
         }
-        return targetAnnotations;
+        return constructor.getParameterAnnotations();
     }
 
     public static class MethodInheritanceComparator