Returning back to an Activity after calling and closing a Fragment does not change my Activity's lifecycle

Issue

Given an Activity that acts as a Home page (it never closes) that launches various fragments, how to know when the Activity is visible to the user?

From what I have observed, when I open a fragment the lifecycle for the Activity never changes, onPause() is not called. And when I close the fragment, onResume() is not called on my Activity.

Here is how I am starting my fragments, I am using this method and passing the fragment I want to launch to it.

public void addFragment(int containerId, Fragment fragment, boolean addToBackStack) {
    // Check if the fragment has been added already. If so, then
    // don't add the fragment.
    Fragment temp = mFragmentManager.findFragmentByTag(fragment.getClass().getName());
    if(temp != null && temp.isAdded()) {
        return;
    }

    FragmentTransaction ft = mFragmentManager.beginTransaction();

    ft.add(containerId, fragment, fragment.getClass().getName());
    if(addToBackStack) 
        ft.addToBackStack(null);        

    ft.commit();
}

What is the methodology for indicating that my Activity is visible again? Thanks in advance!

Solution

in the oncreate method of your home activity, call

mFragmentManager.addOnBackStackChangedListener(this) ;

and then define

@Override
public void onBackStackChanged() {
    int backStackCount = mFragmentManager.getBackStackEntryCount();
    if(backStackCount == 0) {} //back to home screen
}

Answered By - Tim Mutton