Android: How to increase badge from view pager fragment of MainActivity?

Question

I've created badge in MainActivity. It's working perfectly from activity. But in MainActivity, I've taken ViewPager and I need to increase badge count from fragment. Any idea how to achieve this?

  @Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.cart_menu, menu);

    menuItem = menu.findItem(R.id.action_cart);
    menuItem.setIcon(buildCounterDrawable(count, R.drawable.ic_cart));

    return true;
}

  @Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if (id == R.id.action_cart) {
        Intent intent = new Intent(this, CartActivity.class);
        intent.putExtra("id", orderid);
        startActivityForResult(intent, PICK_REQUEST);
        return true;
    }

    return super.onOptionsItemSelected(item);
}

This is the method for Badge count increment

   private Drawable buildCounterDrawable(int count, int backgroundImageId) {
    LayoutInflater inflater = LayoutInflater.from(this);
    View view = inflater.inflate(R.layout.counter_menuitem_layout, null);
    view.setBackgroundResource(backgroundImageId);

    if (count == 0) {
        View counterTextPanel = view.findViewById(R.id.counterValuePanel);
        counterTextPanel.setVisibility(View.GONE);
    } else {
        TextView textView = (TextView) view.findViewById(R.id.count);
        textView.setText(String.valueOf(count));
    }

    view.measure(
            View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
            View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
    view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());

    view.setDrawingCacheEnabled(true);
    view.setDrawingCacheQuality(View.DRAWING_CACHE_QUALITY_HIGH);
    Bitmap bitmap = Bitmap.createBitmap(view.getDrawingCache());
    view.setDrawingCacheEnabled(false);

    return new BitmapDrawable(getResources(), bitmap);
}

public void doIncrease(int val) {
    count = val;
    invalidateOptionsMenu();
}

On Click of plus button, I need to increase the count. Totally unaware how to achieve this

Answer 1

First Create a new Interface Class

public interface OnStepCompletedListener {
     void onStepCompleted(int position);
}

Now implement this interface in your Activity class.

public class MainActivity extends AppCompatActivity implements OnStepCompletedListener{

and implement the method(in your activity)

@Override
public void onStepCompleted(int position){
//
// invoke method to change the badge number here
//
}

Now inside your fragment. Add this code where you want to change the badge.(inside the '+' button click)

try{
     ((OnStepCompletedListener) getActivity()).onStepCompleted(0);
//This will invoke the implemented method in your activity class. You 
//can pass any type of value through to your activity. Just add the 
//parameter in your interface declaration.
}catch (ClassCastException e){
     e.printStackTrace();
}

Answer 2

Define count variable as static and access it from the menu layout class and thereby put the value of static count onto the textview. I have done adding menu from the fragment and this was the code:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true);
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    // TODO Add your menu entries here
    super.onCreateOptionsMenu(menu, inflater);
}