使用片段通过底部导航栏关闭应用

Question

I am using bottom navigation bar. When I click on each items in bottom navigation, Fragment will replace with another one. when I want to press back I want to exit from application. I think this is easy.

But the problem is here: In every Fragment I have button. if we click on button it will replace with another fragment. if I press back button, I want to go to previous fragment that it was in bottom navigation bar. after this if user pressed back again, the app should exit. what should I do?

Should I use onBackPressed() ?

I used this code BUT not working

boolean pressBackForExit = false;
@Override
public void onBackPressed() {
    if (getSupportFragmentManager().getBackStackEntryCount() == 0){
        pressBackForExit = true;
    }
    if (pressBackForExit){
        finish();
    }
    if (getSupportFragmentManager().getBackStackEntryCount() > 0){
        getSupportFragmentManager().popBackStack();
        if (getSupportFragmentManager().getBackStackEntryCount() == 0){
            pressBackForExit = true;
        }
    }
}

If yes, tell me How?

Answer 1

First you have to get the fragment in which you are now. Like you want back from only BottomFragments then put all BottomFragments there if yes, then onBackPress();

   Fragment f = getActivity().getFragmentManager().findFragmentById(R.id.fragment_container);
      if (f instanceof NavBottomOneFragment ) {
            onBackPressed();
       }

Try with below code, Put this code on your Activity Class. This is the code for double press to exit the app.

boolean doubleBackToExitPressedOnce = false;

 @Override
public void onBackPressed() {
    if (doubleBackToExitPressedOnce) {
        super.onBackPressed();
        return;
    }
    this.doubleBackToExitPressedOnce = true;
    Toast.makeText(this, "Press again to exit..", Toast.LENGTH_SHORT).show();
    new Handler().postDelayed(new Runnable() {

        @Override
        public void run() {
            doubleBackToExitPressedOnce=false;
        }
    }, 2000);
}

Answer 2

This can be done by sing two containers One for background fragments ie for tabs switching Second for button clicks on fragment suppose the container id is fragment_container now in your activity onBackPressed method do following

@Override public void onBackPressed() {

 Fragment frag = getSupportFragmentManager().findFragmentById(R.id.fragment_container);
 if (frag != null){ getSupportFragmentManager().beginTransaction().remove(frag).commit();
return;                
}

        super.onBackPressed();
    }

Answer 3

1.Override activity's onBackPressed() method

public void onBackPressed() {
    finish()
}