Attempt to invoke interface method on a null object reference

[ziadkiwan]

Hello LawLoretienne,
Thank you for this great image gallery ! while i was implement the gallery i face a null object reference exception
My Code:

Intent intent = new Intent(MainActivity.this, ImageGalleryActivity.class);
         String path = Environment.getExternalStorageDirectory().toString() + "/req_images/photos";
         Log.d("Files", "Path: " + path);
         File directory = new File(path);
         File[] files = directory.listFiles();
         Log.d("Files", "Size: "+ files.length);
         String[] images = new String[files.length];
         for (int i = 0; i < files.length; i++)
         {
             images[i] = path+"/"+files[i].getName();
             Log.d("Files", "FileName:" + path+"/"+files[i].getName());
         }
         Log.d("Files",images.length+"~~");
         Bundle bundle = new Bundle();
         bundle.putStringArrayList(ImageGalleryActivity.KEY_IMAGES, new ArrayList<>(Arrays.asList(images)));
         bundle.putString(ImageGalleryActivity.KEY_TITLE, "Gallery");
         intent.putExtras(bundle);

         startActivity(intent);

The Error i'm getting:

java.lang.NullPointerException: Attempt to invoke interface method 'void com.etiennelawlor.imagegallery.library.adapters.ImageGalleryAdapter$ImageThumbnailLoader.loadImageThumbnail(android.widget.ImageView, java.lang.String, int)' on a null object reference
at com.etiennelawlor.imagegallery.library.activities.ImageGalleryActivity.loadImageThumbnail(ImageGalleryActivity.java:101)
at com.etiennelawlor.imagegallery.library.adapters.ImageGalleryAdapter.onBindViewHolder(ImageGalleryAdapter.java:58)
at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5471)
at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5504)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4741)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4617)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1994)
at android.support.v7.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:528)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1353)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:574)
at android.support.v7.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:170)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3028)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2906)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3283)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1743)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1586)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1495)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:336)
at android.widget.FrameLayout.onLayout(FrameLayout.java:273)
at com.android.internal.policy.PhoneWindow$DecorView.onLayout(PhoneWindow.java:2678)
at android.view.View.layout(View.java:16653)
at android.view.ViewGroup.layout(ViewGroup.java:5438)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2198)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1958)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1134)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6050)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:860)
at android.view.Choreographer.doCallbacks(Choreographer.java:672)
at android.view.Choreographer.doFrame(Choreographer.java:608)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:846)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.jav

if you can point me at the error i would be grateful i added the activity you requested to the manifest file, and i'm attempting to launch the intent from a actionbar button click, thank you!

[ziadkiwan]

Never mind! didn't read the readme well ❌ thank you!

[lawloretienne]

oh it works now? ya I tried to be a thorough as possible about the usage in the README.

[ziadkiwan]

Yeah but please put the important note after the implementation directly i got a question:
the gallery got no controls like delete picture get path etc ?

[ziadkiwan]

one more thing if you want i can help you rewrite the readme 👍 so it's easier to be used by everyone!

[lawloretienne]

sure, what do you think needs to change?

[ziadkiwan]

First you gotta Explain that Android Graphics Pallete is required and how to import it, then explain how to implement the methods and show the code that needs to be put in the methods (i copy pasted them from them source code of your application) then explain that the application works on URI not main file path and to make the application works on Path you can make a small work around in the two methods which is :
Picasso.with(iv.getContext()) .load(Uri.fromFile(new File(imageUrl))) .resize(width, 0) .into(iv, new Callback() {

[ziadkiwan]

i got a small question if you can help me where i can reach the callback of the imageview(smallones not fullscreen) so i make it on long press display a menu to delete the image

[lawloretienne]

ImageGalleryAdapter has an OnImageClickListener interface. The class that calls setOnImageClickListener() on this adapter can set up the click listener. You can similarly add an additional interface to this adapter.

public interface OnImageLongClickListener {
    void onImageLongClick(int position);
}

[ziadkiwan]

Oh Okay! thank you! i will looking through it :)

[ghost]

@lawloretienne Hi,

I got the same issue as ziadkiwan got. I am not sure how to use Pallete in this case. Kindly, help me execute the code. Thanks in advance.