dynamic close an Activity and fragment

Question

this is my first question.I am using below code for remove fragment:

    private boolean returnBackStackImmediate(FragmentManager fm) {

        List<Fragment> fragments = fm.getFragments();
        if (fragments != null && fragments.size() > 0) {
            for (Fragment fragment : fragments) {
                if (fragment.getFragmentManager().getBackStackEntryCount() > 0) {
                    if (fragment.getFragmentManager().popBackStackImmediate()) {
                        return true;
                    } else {
                        return returnBackStackImmediate(fragment.getChildFragmentManager());
                    }
                }
            }
        }


    return false;
}

Now,I want after remove fragment, if user click on Back button again, my activity be close.for that I have added these codes into my Activity:

    @Override
public void onBackPressed() {

    if (getSupportFragmentManager().getFragments() == null) {
        finish();
    } else {

        if (!returnBackStackImmediate(getSupportFragmentManager())) {
            super.onBackPressed();
        }
    }

}

but when I press back button and remove fragment and press again I got this error:

 java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentManager android.support.v4.app.Fragment.getFragmentManager()' on a null object reference
                                                                             at com.safarayaneh.notify.activities.MainActivity.returnBackStackImmediate(MainActivity.java:501)
                                                                             at com.safarayaneh.notify.activities.MainActivity.onBackPressed(MainActivity.java:488)
                                                                             at android.app.Activity.onKeyUp(Activity.java:2477)
                                                                             at android.view.KeyEvent.dispatch(KeyEvent.java:2664)
                                                                             at android.app.Activity.dispatchKeyEvent(Activity.java:2730)

I know fragment is null but which condition can I use for this situation?

dude I know what is nullPointer. but in my situation how could i solve that? — Groot, Oct 30 '17 at 08:46
You are checking on null and that is a great start, but on the same line you are trying to get the size. I think that is the problem. Can you do the if statement for the null check separate from the size check? — H. Hakvoort, Oct 30 '17 at 08:48
Try to check back stack fragment size inside onBackPressed() like if (getSupportFragmentManager(). getBackStackEntryCount() <= 0) {finish()} — Haresh Chhelana, Oct 30 '17 at 08:49
@H.Hakvoort into onBackPressed method I have this statement `getSupportFragmentManager().getFragments() == null`.I've checked first but seems this statement does not work — Groot, Oct 30 '17 at 08:50

Pritesh - ɐʎıɥpɐΛ ɥsǝʇᴉɹꓒ · Accepted Answer · 2017-10-30T08:56:22.433

4

try this

@Override
public void onBackPressed() {

    int count = getSupportFragmentManager().getBackStackEntryCount();

    if (count == 0) {
        super.onBackPressed();

    } else {
         getSupportFragmentManager().popBackStackImmediate();
    }

}

edited Oct 30 '17 at 08:56

answered Oct 30 '17 at 08:51

Pritesh - ɐʎıɥpɐΛ ɥsǝʇᴉɹꓒ

758
1
6
19

I have already used this way but in this way user will remove completely fragment and will back into main activity. but I want user return just one step to back. – Groot Oct 30 '17 at 08:55
@Groot check updated ans – Pritesh - ɐʎıɥpɐΛ ɥsǝʇᴉɹꓒ Oct 30 '17 at 08:56
but the only problem is when 3 fragment is removed from fm .the user must 3 time click on back press button till can exit from activity :-) – Groot Oct 30 '17 at 09:11
@Groot you can handle using condition or don't add fragment to backstack – Pritesh - ɐʎıɥpɐΛ ɥsǝʇᴉɹꓒ Oct 30 '17 at 09:16
I added backstack inthis way: `((AppCompatActivity) activity).getSupportFragmentManager() .beginTransaction().replace(R.id.attachmentContainer, fragment) .addToBackStack(null).commit();` – Groot Oct 30 '17 at 09:18
remove line `addToBackStack(null)` this will work – Pritesh - ɐʎıɥpɐΛ ɥsǝʇᴉɹꓒ Oct 30 '17 at 09:19
I have removed `addToBackStack(null)`but when I press backpress my activity is finished. – Groot Oct 30 '17 at 09:24
update your question with the code where you change fragment – Pritesh - ɐʎıɥpɐΛ ɥsǝʇᴉɹꓒ Oct 30 '17 at 09:26

score 0 · Answer 2 · answered Oct 30 '17 at 08:50

0

Use getActivity().finish(); to finish Activity from fragment

getActivity().finish();

answered Oct 30 '17 at 08:50

Mallikarjuna

874
6
17

3

First try to understand question than provide your answer and have you think this really solve given problem? – Haresh Chhelana Oct 30 '17 at 08:51

score 0 · Answer 3 · answered Oct 30 '17 at 08:55

I am not sure why you are trying to code this all manually. If you add your fragments to your activity as follows:

  getSupportFragmentManager().beginTransaction().replace(R.id.***YOUR TARGET FRAME ID***, fragment, "some fragment tag")
                .addToBackStack(null)
                .commit();

Then the activity should handle the backstack stuff automatically. I.e. don't need to do anything with onBackPressed. When there's no more fragments in the backstack, the activity will close.

If there's a specific reason you're doing this manually let me know and I'll delete this answer (but you may need to update the question, as this simple approach does answer your question as it stands!)

dynamic close an Activity and fragment

3 Answers3

Use getActivity().finish(); to finish Activity from fragment