onBackPressed() application is not closing

Question

I have 3 activities 1st is login 2nd is registration 3rd home activity (Bottom_nav) with bottom navigation and have 3 fragments A,B,C.

Login activity is launcher activity.

In login user is already login or not is checked If user is not logged in it redirected to registration activity Else to to home activity.

I have implemented onBackPressed() in home activity But on double pressing back button activity get Paused and get resumed.

Here is my code:

 boolean doubleBackToExitPressedOnce = false;

@Override
public void onBackPressed() {
    if (doubleBackToExitPressedOnce) {
        super.onBackPressed();
        Bottom_nav.this.finish();
        return;
    }

    this.doubleBackToExitPressedOnce = true;
    Toast.makeText(this, "Please click BACK again to exit", Toast.LENGTH_SHORT).show();

    new Handler().postDelayed(new Runnable() {

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




private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.navigation_home:
                getSupportFragmentManager().beginTransaction().replace(R.id.MainFrame, new HomeFragment()).commit();
                return true;
            case R.id.navigation_dashboard:
                getSupportFragmentManager().beginTransaction().replace(R.id.MainFrame, new ProfileFragment()).addToBackStack(null).commit();
                return true;
            case R.id.navigation_notifications:
                getSupportFragmentManager().beginTransaction().replace(R.id.MainFrame, new NotificationFragment()).addToBackStack(null).commit();
                return true;
        }
        return false;
    }
};

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bottom_nav);

    getSupportFragmentManager().beginTransaction().add(R.id.MainFrame, new HomeFragment()).commit();
    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);

}

This is log

V/FA: Recording user engagement, ms: 2650
V/FA: Activity paused, time: 132340044
D/FA: Logging event (FE): user_engagement(_e), 
Bundle[{firebase_event_origin(_o)=auto, engagement_time_msec(_et)=2650, 
firebase_screen_class(_sc)=Bottom_nav, 
firebase_screen_id(_si)=-4687850249260059972}]
D/FA: Logging event (FE): screen_view(_vs), 
Bundle[{firebase_event_origin(_o)=auto, 
firebase_previous_class(_pc)=Bottom_nav, 
firebase_previous_id(_pi)=-4687850249260059972, 
firebase_screen_class(_sc)=RegisterPhoneActivity, 
firebase_screen_id(_si)=-4687850249260059974}]
V/FA: onActivityCreated
V/FA: Activity resumed, time: 132340054
V/FA: Screen exposed for less than 1000 ms. Event not sent. time: 184
V/FA: Activity paused, time: 132340135
D/FA: Logging event (FE): screen_view(_vs), 
Bundle[{firebase_event_origin(_o)=auto, 
firebase_previous_class(_pc)=RegisterPhoneActivity, 
firebase_previous_id(_pi)=-4687850249260059974, 
firebase_screen_class(_sc)=Bottom_nav, 
firebase_screen_id(_si)=-4687850249260059971}]
V/FA: Activity resumed, time: 132340244
W/PathParser: Points are too far apart 4.000000000000002
Points are too far apart 4.000000000000002
W/PathParser: Points are too far apart 4.000002058290173
Points are too far apart 4.000002058290173
W/PathParser: Points are too far apart 4.000001624254724
W/PathParser: Points are too far apart 4.000002923700373
Points are too far apart 4.000002923700373
W/PathParser: Points are too far apart 4.00000093640932
V/FA: Inactivity, disconnecting from the service

where am i going wrong? i didnt find any relevant ans to this

Answer 1

if you Launcher Screen is Login then use finishAffinity() method that will finish the current activity and all parent activities, but it works only in Android 4.1 or higher.

if (doubleBackToExitPressedOnce) {
    super.onBackPressed();
    Bottom_nav.this.finishAffinity();
    return;
}

If you don't want to backtraced in the fragment then use this.

FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.container_body, fragment);
        fragmentTransaction.addToBackStack(null);
        fragmentTransaction.commit();

or you can change in your ways like

    getSupportFragmentManager().beginTransaction().replace(R.id.MainFrame, new HomeFragment()).addToBackStack(null).commit();