Uses of fragment tags

Question

In Android, you can set a tag for a Fragment in a FragmentTransaction.

Why would I need to set a tag for a Fragment?

And is it good practice if a Fragment ch

Answer 1

Fragment tags can be used to avoid recreating a Fragment on Activity orientation change.

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.photos_image_pager);

    MyFragment fragment;
    if (savedInstanceState != null) {
        fragment = (MyFragment) getFragmentManager()
            .findFragmentByTag("my_fragment_tag");
    } else {
        fragment = new MyFragment();
        fragment.setArguments(getIntent().getExtras());
        getFragmentManager()
            .beginTransaction()
            .add(android.R.id.content, fragment, "my_fragment_tag")
            .commit(); 
    }
}

The Activity is recreated on orientation change, and its onCreate(...) method is called. If the Fragment was created before the Activity was destroyed and was added to the FragmentManager with a tag, it can now be retrieved from the FragmentManager by the same tag.

For a longer discussion on how it can be used, see:

• ViewPager and fragments - what's the right way to store fragment's state?