Migrate the source base to Kotlin

.codecov.yml

@@ -4,7 +4,7 @@ coverage:
   range: "45...100"
 
   status:
-    project: 
+    project:
       default:
         target: 45%
     patch: yes

.github/workflows/ci.yml

@@ -0,0 +1,28 @@
+# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-gradle
+
+name: Java CI with Gradle
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - '**'
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up JDK 8
+        uses: actions/setup-java@v2
+        with:
+          java-version: '8'
+          distribution: 'adopt'
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+      - name: Build with Gradle
+        run: ./gradlew build
+      - run: pip install --user codecov
+      - run: mkdir "$ANDROID_HOME/licenses" || true
+      - run: echo "24333f8a63b6825ea9c5514f83c2829b004d1fee" >> "$ANDROID_HOME/licenses/android-sdk-license"
+      - run: ./gradlew clean jacocoTestReport

bolts-tasks/build.gradle

@@ -6,30 +6,19 @@
 apply plugin: 'java'
 apply plugin: 'maven'
 
-configurations {
-    provided
-}
-
-sourceSets {
-    main {
-        compileClasspath += configurations.provided
-    }
-}
-
 dependencies {
-    provided 'com.google.android:android:4.1.1.4'
-    testImplementation 'junit:junit:4.12'
+    compileOnly 'com.google.android:android:4.1.1.4'
+    testImplementation 'junit:junit:4.13.2'
 }
 
-
 javadoc.options.addStringOption('Xdoclint:none', '-quiet')
 
 task sourcesJar(type: Jar) {
     classifier = 'sources'
     from sourceSets.main.allJava
 }
 
-task javadocJar (type: Jar, dependsOn: javadoc) {
+task javadocJar(type: Jar, dependsOn: javadoc) {
     classifier = 'javadoc'
     from javadoc.destinationDir
 }
@@ -45,10 +34,6 @@ artifacts {
 
 apply plugin: 'jacoco'
 
-jacoco {
-    toolVersion = '0.7.1.201405082137'
-}
-
 jacocoTestReport {
     group = "Reporting"
     description = "Generate Jacoco coverage reports after running tests."
@@ -59,3 +44,8 @@ jacocoTestReport {
 }
 
 //endregion
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_1_8
+    targetCompatibility = JavaVersion.VERSION_1_8
+}

bolts-tasks/src/main/java/com/parse/boltsinternal/AggregateException.java

@@ -23,7 +23,7 @@ public class AggregateException extends Exception {
 
     private static final String DEFAULT_MESSAGE = "There were multiple errors.";
 
-    private List<Throwable> innerThrowables;
+    private final List<Throwable> innerThrowables;
 
     /**
      * Constructs a new {@code AggregateException} with the current stack trace, the specified detail
@@ -103,7 +103,7 @@ public void printStackTrace(PrintWriter err) {
      */
     @Deprecated
     public List<Exception> getErrors() {
-        List<Exception> errors = new ArrayList<Exception>();
+        List<Exception> errors = new ArrayList<>();
         if (innerThrowables == null) {
             return errors;
         }
@@ -123,7 +123,7 @@ public List<Exception> getErrors() {
      */
     @Deprecated
     public Throwable[] getCauses() {
-        return innerThrowables.toArray(new Throwable[innerThrowables.size()]);
+        return innerThrowables.toArray(new Throwable[0]);
     }
 
 }

bolts-tasks/src/main/java/com/parse/boltsinternal/AndroidExecutors.java

@@ -34,14 +34,8 @@
  */
 /* package */ final class AndroidExecutors {
 
+    /* package */ static final long KEEP_ALIVE_TIME = 1L;
     private static final AndroidExecutors INSTANCE = new AndroidExecutors();
-
-    private final Executor uiThread;
-
-    private AndroidExecutors() {
-        uiThread = new UIThreadExecutor();
-    }
-
     /**
      * Nexus 5: Quad-Core
      * Moto X: Dual-Core
@@ -55,7 +49,11 @@ private AndroidExecutors() {
     private static final int CPU_COUNT = Runtime.getRuntime().availableProcessors();
     /* package */ static final int CORE_POOL_SIZE = CPU_COUNT + 1;
     /* package */ static final int MAX_POOL_SIZE = CPU_COUNT * 2 + 1;
-    /* package */ static final long KEEP_ALIVE_TIME = 1L;
+    private final Executor uiThread;
+
+    private AndroidExecutors() {
+        uiThread = new UIThreadExecutor();
+    }
 
     /**
      * Creates a proper Cached Thread Pool. Tasks will reuse cached threads if available
@@ -72,7 +70,7 @@ public static ExecutorService newCachedThreadPool() {
                 CORE_POOL_SIZE,
                 MAX_POOL_SIZE,
                 KEEP_ALIVE_TIME, TimeUnit.SECONDS,
-                new LinkedBlockingQueue<Runnable>());
+                new LinkedBlockingQueue<>());
 
         allowCoreThreadTimeout(executor, true);
 
@@ -95,7 +93,7 @@ public static ExecutorService newCachedThreadPool(ThreadFactory threadFactory) {
                 CORE_POOL_SIZE,
                 MAX_POOL_SIZE,
                 KEEP_ALIVE_TIME, TimeUnit.SECONDS,
-                new LinkedBlockingQueue<Runnable>(),
+                new LinkedBlockingQueue<>(),
                 threadFactory);
 
         allowCoreThreadTimeout(executor, true);

bolts-tasks/src/main/java/com/parse/boltsinternal/BoltsExecutors.java

@@ -18,15 +18,6 @@
 /* package */ final class BoltsExecutors {
 
     private static final BoltsExecutors INSTANCE = new BoltsExecutors();
-
-    private static boolean isAndroidRuntime() {
-        String javaRuntimeName = System.getProperty("java.runtime.name");
-        if (javaRuntimeName == null) {
-            return false;
-        }
-        return javaRuntimeName.toLowerCase(Locale.US).contains("android");
-    }
-
     private final ExecutorService background;
     private final ScheduledExecutorService scheduled;
     private final Executor immediate;
@@ -39,6 +30,14 @@ private BoltsExecutors() {
         immediate = new ImmediateExecutor();
     }
 
+    private static boolean isAndroidRuntime() {
+        String javaRuntimeName = System.getProperty("java.runtime.name");
+        if (javaRuntimeName == null) {
+            return false;
+        }
+        return javaRuntimeName.toLowerCase(Locale.US).contains("android");
+    }
+
     /**
      * An {@link java.util.concurrent.Executor} that executes tasks in parallel.
      */
@@ -69,7 +68,7 @@ static Executor immediate() {
      */
     private static class ImmediateExecutor implements Executor {
         private static final int MAX_DEPTH = 15;
-        private ThreadLocal<Integer> executionDepth = new ThreadLocal<>();
+        private final ThreadLocal<Integer> executionDepth = new ThreadLocal<>();
 
         /**
          * Increments the depth.

bolts-tasks/src/main/java/com/parse/boltsinternal/CancellationToken.java

@@ -64,6 +64,6 @@ public String toString() {
         return String.format(Locale.US, "%s@%s[cancellationRequested=%s]",
                 getClass().getName(),
                 Integer.toHexString(hashCode()),
-                Boolean.toString(tokenSource.isCancellationRequested()));
+                tokenSource.isCancellationRequested());
     }
 }

bolts-tasks/src/main/java/com/parse/boltsinternal/CancellationTokenSource.java

@@ -105,14 +105,11 @@ private void cancelAfter(long delay, TimeUnit timeUnit) {
             cancelScheduledCancellation();
 
             if (delay != -1) {
-                scheduledCancellation = executor.schedule(new Runnable() {
-                    @Override
-                    public void run() {
-                        synchronized (lock) {
-                            scheduledCancellation = null;
-                        }
-                        cancel();
+                scheduledCancellation = executor.schedule(() -> {
+                    synchronized (lock) {
+                        scheduledCancellation = null;
                     }
+                    cancel();
                 }, delay, timeUnit);
             }
         }
@@ -187,7 +184,7 @@ public String toString() {
         return String.format(Locale.US, "%s@%s[cancellationRequested=%s]",
                 getClass().getName(),
                 Integer.toHexString(hashCode()),
-                Boolean.toString(isCancellationRequested()));
+                isCancellationRequested());
     }
 
     // This method makes no attempt to perform any synchronization itself - you should ensure