How to fix recycler view not using data error?

Question

Java

Created a recycler view with GridLayoutManager however it doesn't want to read data from prepareGalleryData(). Gives an error message

java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.add(java.lang.Object)' on a null object reference

And in the code this error points to two lines

at com.example.asus.testapp147.UserProfile_PhotoFragment.prepareGalleryData(UserProfile_PhotoFragment.java:58)

points to line 58 ( galleryList.add(gallery);) in

GalleryGridObject gallery = new GalleryGridObject(R.drawable.city);
        galleryList.add(gallery);

Here is the complete codeprepareGalleryData()

private void prepareGalleryData()
    {
        GalleryGridObject gallery = new GalleryGridObject(R.drawable.city);
        galleryList.add(gallery);

        gallery = new GalleryGridObject(R.drawable.city);
        galleryList.add(gallery);

        gallery = new GalleryGridObject(R.drawable.city);
        galleryList.add(gallery);

        mAdapter.notifyDataSetChanged();
    }

And on line 50 in the onCreateViewfragment
prepareGalleryData();
How to fix this error? (I'll throw off the full code of the fragment and adapter in the comments)

Answer 1

The galleryList field is not initialized anywhere, i.e. is always null.