Android, How to restart/refresh a fragment from FragmentActivty?

Question

In my FragmentActivity I have a fragment. This fragment loads data from server. I want we user clicks on refresh button then I call a method in fragment and do refreshing pr

Answer 1

Executing this

onRefreshSelected = (OnRefreshSelected) MainScreen.this;

you are assigning your activity in onRefreshSelected field, trying to cast it to your interface, but your activity doesn't implement the interface, that's why ClassCastException raised.

Instead use something like this

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
                case R.id.menu_refresh:
                    CategoryFragment fragment = (CategoryFragment) getFragmentManager()
                        .findFragmentById(R.id.category_fragment);
                    if (fragment != null) {
                        fragment.getData();
                    }
                    return true;
                default:
                    return super.onOptionsItemSelected(item);
    }

Your activity can call methods in the fragment by acquiring a reference to the Fragment from FragmentManager, using findFragmentById() or findFragmentByTag().

Answer 2

I agree with biegleux... But my suggestion is

public class CategoryFragment extends Fragment{

   private static CategoryFragment categoryFrag;

    private CategoryFragment(){}

    public static CategoryFragment getInstance(){
        if(null == categoryFrag){
            categoryFrag = new CategoryFragment();
        }

        return categoryFrag;
    }

    public void  getData(){
       /*** Screen Refresh code****/
    }
} 

I your active when he selects option

@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
                case R.id.menu_refresh:
                    CategoryFragment fragment = CategoryFragment.getInstance();
                     fragment.getData();

                    return true;
                default:
                    return super.onOptionsItemSelected(item);
    }