NullPointerException - ArrayList<URI>

[L Vasquez]

I am trying to take/pick four pictures in a row and add them each to an ArrayList in order to be able to show one at a time in an ImageView. Once I take the very last picture however, I get the following exception:

    FATAL EXCEPTION: main
    Process: my.package.myapplication, PID: 11009
    java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1, result=-1, data=null} to activity {my.package.myapplication/my.package.myapplication.Person1Screen}: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.ArrayList.add(int, java.lang.Object)' on a null object reference
    at android.app.ActivityThread.deliverResults(ActivityThread.java:3759)
    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3802)
    at android.app.ActivityThread.access$1400(ActivityThread.java:157)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1400)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5477)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
    
    Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.ArrayList.add(int, java.lang.Object)' on a null object reference
    at my.package.myapplication.Person1Screen.onActivityResult(Person1Screen.java:210)
    at android.app.Activity.dispatchActivityResult(Activity.java:6650)
    at android.app.ActivityThread.deliverResults(ActivityThread.java:3755)
    at android.app.ActivityThread.handleSendResult(ActivityThread.java:3802) 
    at android.app.ActivityThread.access$1400(ActivityThread.java:157) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1400) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5477) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

The last line of my OnActivityResult is where the error occurs:
   

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
            if (resultCode == RESULT_OK) {
                if (requestCode == REQUEST_TAKE_PHOTO) {
                    final boolean isCamera;
                    if (data == null) {
                        isCamera = true;
                    } else {
                        final String action = data.getAction();
                        if (action == null) {
                            isCamera = false;
                        } else {
                            isCamera = action.equals(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                        }
                    }
                    Uri selectedImageUri;
                    if (isCamera) {
                        selectedImageUri = outputFileUri;
                    } else {
                        selectedImageUri = data == null ? null : data.getData();
                    }
                   // mainView.setImageURI(selectedImageUri);
                    happyList.add(pictureCounter, selectedImageUri);
                }
            }
        } 

and my takePhotoIntent is:
   

    private void dispatchTakePictureIntent() {
        pictureCounter = 0;
        happyList = new ArrayList<>();
        for(int i = 0; i < 4; i++) {
            pictureCounter++;
            Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
            if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
                // Create the File where the photo should go
                File photoFile = null;
                try {
                    photoFile = createImageFile();
                    outputFileUri = Uri.fromFile(photoFile);
                } catch (IOException ex) {
                    // Error occurred while creating the File
                }
                // Camera.
                final List<Intent> cameraIntents = new ArrayList<Intent>();
                final Intent captureIntent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
                final PackageManager packageManager = getPackageManager();
                final List<ResolveInfo> listCam = packageManager.queryIntentActivities(captureIntent, 0);
                for (ResolveInfo res : listCam) {
                    final String packageName = res.activityInfo.packageName;
                    final Intent intent = new Intent(captureIntent);
                    intent.setComponent(new ComponentName(res.activityInfo.packageName, res.activityInfo.name));
                    intent.setPackage(packageName);
                    intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photoFile));
                    cameraIntents.add(intent);
                }
                // Filesystem.
                final Intent galleryIntent = new Intent();
                galleryIntent.setType("image/*");
                galleryIntent.setAction(Intent.ACTION_GET_CONTENT);
                // Chooser of filesystem options.
                final Intent chooserIntent = Intent.createChooser(galleryIntent, "Select Source");
                // Add the camera options.
                chooserIntent.putExtra(Intent.EXTRA_INITIAL_INTENTS, cameraIntents.toArray(new Parcelable[cameraIntents.size()]));
                startActivityForResult(chooserIntent, REQUEST_TAKE_PHOTO);
            }
        }
    }

Can anybody please help me understand why my array becomes null as soon as I take my fourth picture?

[Norm Radder]

Once I take the very last picture

What is different about the "last" picture?  How does the program know it is the last picture?

[L Vasquez]

Norm Radder wrote:

Once I take the very last picture

What is different about the "last" picture?  How does the program know it is the last picture?

I simply looped the dispatchTakePictureIntent 4 times. When I run the program, it lets me take/choose 3 pictures and after the fourth it crashes.

[L Vasquez]

Norm Radder wrote:

Once I take the very last picture

What is different about the "last" picture?  How does the program know it is the last picture?

Just tried without the loop and only taking one picture. Program crashes the same.

[Norm Radder]

only taking one picture. Program crashes the same.

Are you sure you know where the NPE happens?  How many times is the onActivityResult method called?  Is there an extra call somewhere?

[L Vasquez]

Norm Radder wrote:

after the fourth it crashes.

Does the same thing happen with  fewer or more than 4?

Happens with fewer/more (i.e. with two loops, on the second loop it crashes; with only one, it crashes on the one picture)

[L Vasquez]

Norm Radder wrote:

Once I take the very last picture

What is different about the "last" picture?  How does the program know it is the last picture?

I moved

        happyList = new ArrayList<>();

to my onCreate method instead of instantiating it in the dispatchTakePhotoIntent method and no crash. When I do

Log.d("array", happyList.toString());

, I get array:[] printed out..