Why is .setImageBitmap() not assigning an image to an ImageView object?

Question

I've a method that read throughs external storage space for images. I want to store these images in an ImageView ArrayList. To do this I've defined the folder which I want to search through and have created a Bitmap variable that is assigned the image I want to convent to ImageView however the .setImageBitmap(saveImage) doesn't assign to my Imageview object.

Here's the code:

 private ArrayList<ImageView> getData() {

        ImageView singleImage = null;
        final ArrayList<ImageView> addImage = new ArrayList<>();
        File retrieveImages = new File(Environment.getExternalStoragePublicDirectory(
                Environment.DIRECTORY_PICTURES), "/WordResolver");

        for(File countImages : retrieveImages.listFiles()) {

            if(countImages.isFile() && (countImages.getName().endsWith(".jpg"))) {

                Bitmap saveImage = BitmapFactory.decodeFile(countImages.getAbsolutePath());
                singleImage.setImageBitmap(saveImage); //Fails here
                addImage.add(singleImage);
            }

        }

        return addImage;
    }

Here's proof that an image is being read and stored in the BitMap object.

And here's the stacktrace that is throwing a NPE error even though the ImageView should be assigned with an Image.

05-20 03:13:38.220 8641-8641/com.example.aaron.wordresolver E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.aaron.wordresolver, PID: 8641 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.aaron.wordresolver/com.example.aaron.wordresolver.PictureGallery}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$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 android.widget.ImageView.setImageBitmap(android.graphics.Bitmap)' on a null object reference at com.example.aaron.wordresolver.PictureGallery.getData(PictureGallery.java:78) at com.example.aaron.wordresolver.PictureGallery.onCreate(PictureGallery.java:45) at android.app.Activity.performCreate(Activity.java:6237) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:148) at android.app.ActivityThread.main(ActivityThread.java:5417) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

You are not assigning any imageview to "singleImage" thats why it is null. — Ram Prakash Bhat, May 20 '16 at 07:23
Is `singleImage.setImageBitmap(saveImage);` not assigning a _bitmap_ to the ImageView thus giving it a value? — COYG, May 20 '16 at 07:28
@COYG: do like this singleImage = (ImageView)view.findViewById(R.id.your_imageview); — Ram Prakash Bhat, May 20 '16 at 08:20

score 1 · Answer 1 · edited May 20 '16 at 08:26

1

singleImage is not initialize properly, assign it null is not enough.

Initialize singleImage in OnCreate() :

singleImage = (ImageView)findViewById(R.id.image);

remove :

ImageView singleImage = null;

and run getData() after initialization.

edited May 20 '16 at 08:26

Vivek_Neel

1,343
1
14
25

answered May 20 '16 at 07:30

Shadwork

97
4

This imageview is going to store images from the external storage. Therefore I can't initialize it with `findViewById(R.id.image);` – COYG May 20 '16 at 16:01
ImageView is container connected to screen layout. You still need initialize it if you don`t want using View on screen. Just initialize it with Context constructor ImageView singleImage = new ImageView(context); – Shadwork May 23 '16 at 07:39

Why is .setImageBitmap() not assigning an image to an ImageView object?

1 Answers1