How to keep only one instance of a fragment, when switching with NavigationDrawer?

Question

My App starts with a AddressFragment. From the NavigationDrawer I start (amongst others) a new AddressFragment with:

getSupportFragmentManag         


        

Answer 1

This is tested answer, Hope this will help you First Make these field globally in MainActivity

private static final int TIME_INTERVAL = 2000; 
private long mBackPressed;
private FragmentManager fm;
private FragmentTransaction ft;
private DrawerLayout drawer;

Now in onNavigationItemSelected() implement like that

    @Override
public boolean onNavigationItemSelected(MenuItem item) {
Fragment fragment = null;
Class fragmentClass = null;
switch (item.getItemId()) {
case R.id.nav_home:
fragmentClass = Fragment.class;//this is MainAvctivty extends AppCompatActivity
break;
case R.id.nav_f1:
fragmentClass = FragmentOne.class;
break;
case R.id.nav_f2:
fragmentClass = FragmentTwo.class;
break;
case R.id.nav_f3:
fragmentClass = FragmentThree.class;
break;
case R.id.nav_f4:
fragmentClass = FragmentFour.class;
break;
case R.id.nav_f5:
fragmentClass = FragmentFive.class;
break;
default:
fragmentClass = Fragment.class;
}
try {
fragment = (Fragment) fragmentClass.newInstance();
} catch (Exception e) {e.printStackTrace();}
//Insert the fragment by replacing any existing fragment
fm = getSupportFragmentManager();
ft = fm.beginTransaction();
ft.replace(R.id.frame_container, fragment);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
ft.addToBackStack(null);
ft.commit();
item.setChecked(true);
setTitle(item.getTitle());
drawer.closeDrawers();
return true;
}

Now handle onbackpressed like below

@Override
public void onBackPressed() {
if (drawer != null) {
fm = getSupportFragmentManager();
ft = fm.beginTransaction();
if (drawer.isDrawerOpen(GravityCompat.START)) {
drawer.closeDrawer(GravityCompat.START);
} else if (fm.getBackStackEntryCount() > 0) {
fm.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_CLOSE);
ft.commit();
} else if (mBackPressed + TIME_INTERVAL > System.currentTimeMillis()) {
super.onBackPressed();
} else {
Toast.makeText(this,"Press again to exit the app",Toast.LENGTH_SHORT).show();
}
mBackPressed = System.currentTimeMillis();
}
}