CODEWITHSUNDEEP
androidfragment
user986689
user986689

Reputation: 111

Detect a fragment in the screen

I have a pager that contains three fragments

adapter.addFragment (new PlainColorFragment (Color.red));

adapter.addFragment (new PlainColorFragment (Color.green));

adapter.addFragment (new PlainColorFragment (Color.blue));

My question is whether it is possible to detect that fragmentation has focus or is being displayed to the user.

For example, when the green fragment is the one on screen or has focus, show a "toast" on the screen

I hope I have explained my question correctly.

thanks

Upvotes: 1

Views: 1908

Answers (3)

Catalin Oprea
Catalin Oprea

Reputation: 23

You can create an Interface, implementing it in your Fragment and then, on parent activity, you can implement BackStackChangedListener as in example below:

    public interface MyFragmentOnScreen {

        public void onActiveFragment();
    }

    public class MyFragment extends Fragment implements MyFragmentOnScreen{
      [...]
        @Override
    public void onActiveFragment() {
//Things you should do when your fragment becomes active
}
    }

public class MainActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
[...]
        getSupportFragmentManager().addOnBackStackChangedListener(
                new FragmentManager.OnBackStackChangedListener() {
                    public void onBackStackChanged() {
                        // Update your UI here.
                        Log.v(MainActivity.TAG, "Backstack changed");

                            if (getSupportFragmentManager().findFragmentById(R.id.frMain) instanceof MyFragmentOnScreen) {
                                ((MyFragmentOnScreen) getSupportFragmentManager().findFragmentById(R.id.frMain)).onActiveFragment();
                            }
                        }
                    }
                });
}
}

where frMain is the holder in MainActivity layout for your Fragment.

Upvotes: 0

JRaymond
JRaymond

Reputation: 11782

Simple: 

greenFragment.isVisible();

If you're looking for some kind of event, you would have to manage that manually wherever your fragment switching happens, or in your fragment class, you could execute your code in the fragment's OnHiddenChanged event (double checking, of course, that it is currently visible)

Upvotes: 2

Sam Dozor
Sam Dozor

Reputation: 40754

You could set an OnPageChangedListener to your ViewPager and show a different toast depending on the position.

Upvotes: 0

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