MyFragment.java

   public class MyFragment extends Fragment implements AppBarLayout.OnOffsetChangedListener {
   //..... other code here
   //Initialize appbar
   private AppBarLayout appbar;
   @Override
   public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {		      public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
     //.,.
     appbar = (AppBarLayout) mainView.findViewById(R.id.appbar);
   }
   // Set the content descriptions based on the offset math                                                                                             
   @Override                    
    public void onOffsetChanged(AppBarLayout appBarLayout, int verticalOffset) {
        if (Math.abs(verticalOffset) == appBarLayout.getTotalScrollRange()) {
            contactImage.setContentDescription(getString(R.string.cd_image_collapsed));
        } else if (verticalOffset == 0) {
            contactImage.setContentDescription(getString(R.string.cd_image_expanded));
        } else {
            contactImage.setContentDescription(getString(R.string.cd_image_collapsing));
        }
    }                                                                                                 
    @Override
    public void onResume() {
        super.onResume();
        appbar.addOnOffsetChangedListener(this);
    }

    @Override
    public void onPause() {
        super.onPause();
        appbar.removeOnOffsetChangedListener(this);
    }
}