CODEWITHSUNDEEP
androidandroid-fragmentsandroid-activity
Amarghosh
Amarghosh

Reputation: 59461

Exiting from Activity with only fragments

My app contains one empty activity and a couple of fragments. The onCreate of the activity replaces the empty view in activity_main.xml with a MainFragment that contains some buttons. Each button launches a separate fragment, and user can navigate from one fragment to another, etc.

On the press of back key, the current fragment correctly gets replaced with the previous fragment, until you get to the MainFragment. When user presses back from MainFragment, it hides the main fragment and you see the white empty background of the main activity. But I want to exit from the activity at this point, as that would be the sensible behaviour.

I am able to achieve this by calling super.onBackPressed() for a second time from onBackPressed if there are no fragments left in the fragment manager.

@Override
public void onBackPressed() {
    super.onBackPressed();
    FragmentManager manager = getSupportFragmentManager();
    List<Fragment> fragments = manager.getFragments();
    if (fragments == null || fragments.size() == 0) {
        Log.d(TAG, "No more fragments: exit");
        super.onBackPressed();
    }
}

Is this acceptable thing to do - would it create any issues in the activity workflow? Is there a better/standard way to handle this scenario?

Upvotes: 1

Views: 217

Answers (2)

Alexander Kozubets
Alexander Kozubets

Reputation: 61

You don't really need to override onBackPressed in your Activity. I would suggest implementing a method for adding fragments in your Activity:

protected void addFragment(Fragment fragment, boolean addToBackStack) {
    String tag = fragment.getClass().getName(); //It's optional, may be null
    FragmentTransaction transaction = getSupportFragmentManager()
            .beginTransaction()
            .add(R.id.your_container_id, fragment, tag);

    if (addToBackStack) {
        transaction.addToBackStack(tag);
    }

    transaction.commit();
}

And modify your onCreate method of activity like in the following snippet:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    if (savedInstanceState == null) {
        // Add your fragment only if it is a first launch, 
        // otherwise it will be restored by system 
        addFragment(new YourFirstFragment(), false);
    }
}

For all other fragments use:

addFragment(new OtherFragment(), true);

Upvotes: 0

cherif
cherif

Reputation: 1344

There is no problem to do that, but probably it would be easier if when you add the main fragment to the activity you do NOT call .addToBackStack()

Upvotes: 1

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