I have implemented Navigation Drawer which is a subclass of Activity. I have many fragments in my application. My question goes here
Imagine there are 3 fragments :
Fragment_1 : Fragment_2 : Fragment_3
When I start my application, Fragment_1 is loaded When I click on some components on Fragment_1, I'm navigated to Fragment_2 and so on..
So it's like
Fragment_1 > Fragment_2 > Fragment_3
When I press back key from Fragment_2, I'm navigated back to Fragment_1 But when I press back key from Fragment_3, I'm navigated back to Fragment_1 (instead of Fragment_2)
I want something like this in my application on Back Key press
Fragment_1 < Fragment_2 < Fragment_3
I have used Fragment, FragmentManager, FragmentTransaction as follows :
MyFragment fragment = new MyFragment();
FragmentManager fragmentManager = getFragmentManager();
fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).addToBackStack(null)commit();
and I tried overriding onBackPressed() in my MainActivity :
@Override
public void onBackPressed() {
getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
int count = getFragmentManager().getBackStackEntryCount();
if (count == 0)
super.onBackPressed();
}
Update your Activity#onBackPressed()
method to:
@Override
public void onBackPressed() {
if (getFragmentManager().getBackStackEntryCount() > 0) {
getFragmentManager().popBackStack();
} else {
super.onBackPressed();
}
}
The reason your implementation doesn't work is because the method FragmentManager#popBackStack()
is asynchronous and does not happen right after it is called.
From the documentation:
This function is asynchronous -- it enqueues the request to pop, but the action will not be performed until the application returns to its event loop.