Avoid ConcurrentModificationExceptions in listeners (#88)

Author: natario1

cameraview/src/androidTest/java/com/otaliastudios/cameraview/CameraViewTest.java

@@ -382,6 +382,7 @@ public void testExposureCorrection() {
 
     //region testLocation
 
+    @SuppressWarnings("ConstantConditions")
     @Test
     public void testSetLocation() {
         cameraView.setLocation(50d, -50d);
@@ -554,6 +555,7 @@ public void testVideoQuality() {
 
     //region Lists of listeners and processors
 
+    @SuppressWarnings("UseBulkOperation")
     @Test
     public void testCameraListenerList() {
         assertTrue(cameraView.mListeners.isEmpty());
@@ -571,8 +573,17 @@ public void testCameraListenerList() {
 
         cameraView.clearCameraListeners();
         assertTrue(cameraView.mListeners.isEmpty());
+
+        // Ensure this does not throw a ConcurrentModificationException
+        cameraView.addCameraListener(new CameraListener() {});
+        cameraView.addCameraListener(new CameraListener() {});
+        cameraView.addCameraListener(new CameraListener() {});
+        for (CameraListener test : cameraView.mListeners) {
+            cameraView.mListeners.remove(test);
+        }
     }
 
+    @SuppressWarnings({"NullableProblems", "UseBulkOperation"})
     @Test
     public void testFrameProcessorsList() {
         assertTrue(cameraView.mFrameProcessors.isEmpty());
@@ -592,6 +603,14 @@ public void process(@NonNull Frame frame) {}
 
         cameraView.clearFrameProcessors();
         assertTrue(cameraView.mFrameProcessors.isEmpty());
+
+        // Ensure this does not throw a ConcurrentModificationException
+        cameraView.addFrameProcessor(new FrameProcessor() { public void process(Frame f) {} });
+        cameraView.addFrameProcessor(new FrameProcessor() { public void process(Frame f) {} });
+        cameraView.addFrameProcessor(new FrameProcessor() { public void process(Frame f) {} });
+        for (FrameProcessor test : cameraView.mFrameProcessors) {
+            cameraView.mFrameProcessors.remove(test);
+        }
     }
 
     //endregion

cameraview/src/main/java/com/otaliastudios/cameraview/CameraView.java

@@ -29,6 +29,7 @@
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
 
 import static android.view.View.MeasureSpec.AT_MOST;
 import static android.view.View.MeasureSpec.EXACTLY;
@@ -62,8 +63,8 @@ public class CameraView extends FrameLayout {
     private OrientationHelper mOrientationHelper;
     private CameraController mCameraController;
     private MediaActionSound mSound;
-    /* for tests */ ArrayList<CameraListener> mListeners = new ArrayList<>(2);
-    /* for tests */ ArrayList<FrameProcessor> mFrameProcessors = new ArrayList<>(1);
+    /* for tests */ List<CameraListener> mListeners = new CopyOnWriteArrayList<>();
+    /* for tests */ List<FrameProcessor> mFrameProcessors = new CopyOnWriteArrayList<>();
 
     // Views
     GridLinesLayout mGridLinesLayout;