java.lang.NullPointerException at ImageAdapter.(ImageAdapter.java:41)

Question

I am getting nullpointer exception when i am initializing ImageAdapter object. I have defined my IMageAdapter parameterized Constructor and calling it correctly(hopefully). I don't get where i am going wrong?

I have created separate ImageApdater java class and did not subclassed it, and by gridview for which i created this imageadapter is on a Fragment and this Fragment is Tab.

Here is my ImageAdapter class

public class ImageAdapter extends BaseAdapter {

Context mcontext;
int[] IMAGES;
int[] IMAGE_ID,  IMAGE_PRICE;
String[] IMAGE_NAME,  MODEL_TYPE;

public ImageAdapter(Context context, int[] images, int[] image_id, int [] image_price,   
String[] image_name, String[] model_type) {

    mcontext=context;
    this.IMAGES = images;
    this.IMAGE_ID=image_id;
    this.IMAGE_PRICE=image_price;
    this.IMAGE_NAME=image_name;
    this.MODEL_TYPE=model_type;
}//ImageAdapter Constructor

and i am calling it in Fragment class as below:

public class CommunityGalleryFragment extends Fragment {


    byte[] image = null;
    Bitmap bitmapImage = null;
    Context context;

  // images to be inflated in gallery view

// Images to be stored in database table
int[] IMAGES = { R.drawable.a, R.drawable.g, R.drawable.c,
        R.drawable.h, R.drawable.j, R.drawable.d, R.drawable.f,
        R.drawable.e, R.drawable.i, R.drawable.b };

// Spinner data
String[] VIEWALL_ITEMS = { "View All", "Glaze ", "Ceramic", "Plaster" };
String[] SORT_ITEMS = { "Sort By", "name", "Date" };

// Cursor to get records from table
Cursor initial_cursor;
RMLocalGalleryAdapter rmLocalGalleryAdapter;

// Data to be stored in database table

// Image ID's
int[] IMAGE_ID = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

// Image Price
int[] IMAGE_PRICE = { 32, 76, 25, 30, 50, 22, 33, 55, 65, 43 };
String[] IMAGE_NAME = {"a", "g","c", "h", "j", "d", "f", "e", "i","b"};

// Model Types
String[] MODEL_TYPE = { "Glaze", "Ceramic", "Ceramic", "Ceramic", "Glaze",
        "Glaze", "Plaster", "Plaster", "Plaster", "Plaster" };

String date;
// Declaring views
public Spinner viewAll_spinner, sort_spinner;
GridView gridView;

//boolean fromHomeActivity, fromLocalGallery;


public CommunityGalleryFragment() {}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // inflating communitygallery_fragment layout from layout folder
    this.context = container.getContext();

    View view = inflater.inflate(R.layout.communitygallery_fragment, container, false);

    viewAll_spinner = (Spinner) view    
.findViewById(R.id.communityGallery_spinner_viewAll);
    sort_spinner = (Spinner) view.findViewById(R.id.communityGallery_spinner_sort);

    rmLocalGalleryAdapter = new RMLocalGalleryAdapter(getActivity());
    rmLocalGalleryAdapter.openDB();

    initial_cursor = rmLocalGalleryAdapter.getAllImagesByDate();

    // Setup UI
    gridView = (GridView) view.findViewById(R.id.communityGallery_gridView);


    // inserting data into sqlite database only if there is no data inserted previously
    if (initial_cursor.getCount() == 0) {
        // inserting data in multiple records---- it will be inserted as
        // many as images are available in IMAGES
        for (int i = 0; i < IMAGES.length; i++) {
            byte[] image = convertToByteArray(IMAGES[i]);

            // /calling insertValues method of Adapter class and passing all
            // paramenters
            rmLocalGalleryAdapter.insertValues(image, IMAGE_ID[i],  IMAGE_PRICE[i], 
IMAGE_NAME[i], MODEL_TYPE[i]);
        }// for
    }// if
        // closing cursor to avoid memory leaks
    initial_cursor.close();
    return view;
}// onCreateView

private byte[] convertToByteArray(int image) {
    Resources resources = getResources();
    Drawable drawable = resources.getDrawable(image);
    Bitmap bitmap =  ((BitmapDrawable)drawable).getBitmap();
    ByteArrayOutputStream stream = new ByteArrayOutputStream();
    bitmap.compress( Bitmap.CompressFormat.PNG, 100, stream);
    byte[] bitmapData = stream.toByteArray();

    return bitmapData;
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onActivityCreated(savedInstanceState);

    // creating adapter for " View All" Spinner
    ArrayAdapter<String> viewAll_Adapter = new ArrayAdapter<String>(
            getActivity(), android.R.layout.simple_spinner_dropdown_item, 
VIEWALL_ITEMS);

    // Creating adapter for " Sort By "Spinner
    ArrayAdapter<String> sortBy_Adapter = new ArrayAdapter<String>(
            getActivity(), android.R.layout.simple_spinner_dropdown_item, SORT_ITEMS);

    viewAll_spinner.setAdapter(viewAll_Adapter);
    sort_spinner.setAdapter(sortBy_Adapter);



    // setting ImageAdapter to the gridview


    //View spinner listener to handle selection in spinner
    viewAll_spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> parent, View view,    int position, 
 long id) {
            // TODO Auto-generated method stub

            gridView.setAdapter(new ImageAdapter(context, IMAGES, IMAGE_ID, 
 IMAGE_PRICE, IMAGE_NAME, MODEL_TYPE ));

        }//view spinner 

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            // TODO Auto-generated method stub

        }//view spinner
    });
    sort_spinner.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> parent, View view,    int position, 
long id) {
            // TODO Auto-generated method stub

            gridView.setAdapter(new ImageAdapter(context, IMAGES, IMAGE_ID, 
IMAGE_PRICE, IMAGE_NAME, MODEL_TYPE ));
        }

        @Override
        public void onNothingSelected(AdapterView<?> parent) {
            // TODO Auto-generated method stub

        }
    });

}// onActivityCreated
}

Answer 1

/* this is line 41*/ int view_spinner_id =communityGalleryFragment.viewAll_spinner.getSelectedItemPosition();

So communityGalleryFragment.viewAll_spinner is null. You're trying to use it too early.

If it is a spiner in a fragment as the name implies, you will have to wait for the fragment itself to initialize itself within the fragment lifecycle. In practice it's onCreateView() at earliest.

Also, referencing another class internals like this is not a good design practice.