Handle `BackPressed` when we only have a fragment

Question

I have an Activity and it has only one Fragment. I want to handle backpressed functionality. When user presses back, program should go back to Activity. I know this is very simple but I have tried some solutions that are mentioned on Stackoverflow, but none of them worked. For example I tried this:

public void onBackPressed() {
int count = getFragmentManager().getBackStackEntryCount();

    if (count == 0) {
        super.onBackPressed();
        //additional code
    } else {

        getFragmentManager().popBackStack();
    }
}

https://www.skoumal.com/en/android-handle-back-press-in-fragment/ — IntelliJ Amiya, Sep 16 '18 at 07:14
@IntelliJAmiya I tried your solution but when I press back, program go out. — maryam, Sep 16 '18 at 07:40
You say that have only one fragment, but you are checking if there is another fragment in backStack, is this correct? — Pedro Massango, Sep 16 '18 at 08:13

score 1 · Answer 1 · answered Sep 16 '18 at 07:42

1

Your code seems to be correct. Did you add Fragment to backstack using addToBackStack ? Have a look at this question. It's similar to yours.

answered Sep 16 '18 at 07:42

Adil Iqbal

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3
12

I add Fragment to `addToBackStack` and return to my Activity. But my app show blank activity! – maryam Sep 16 '18 at 08:05
Can you show how you are creating and adding the fragment? May be you're using `SupportFragmentManager` for adding the fragment and `FragmentManager` is returning count 0. – Adil Iqbal Sep 16 '18 at 08:13

score 1 · Accepted Answer · answered Sep 16 '18 at 08:50

As I understand all you want to do is when users press Back key on MainActivity

If there are more than 1 fragments in the back stack just pop out the fragment
If there is only 1 fragment in the back stack, first back press will be ignored and you would like to run some additional code. Then if users press back key again, your MainActivity will be finished.

Change your code to

private boolean ignoredFirstBackPressed = false;

@Override
public void onBackPressed() {
    int count = getFragmentManager().getBackStackEntryCount();
    if (count == 1) {
        // If there is only one fragment in back stack
        if (!ignoredFirstBackPressed) {
            // additional code
            ignoredFirstBackPressed = true;
        } else {
            finish();
        }
    } else {
        getFragmentManager().popBackStack(); // or super.onBackPressed()
    }
}

Handle `BackPressed` when we only have a fragment

2 Answers2