Fragment back stack does not work when extending AppCompatActivity

Question

I'm using the new AppCompatActivity introduced in the AppCompat library version 22.1.

When I extend this Activity, the hardware back button no longer pops the back stack of my Fragments, it closes the Activity instead.

Here is how I'm changing fragments in my activity:

public void changeFragment(Fragment f) {
    FragmentTransaction ft = getFragmentManager().beginTransaction();
    ft.replace(R.id.fragment_holder, f);
    ft.addToBackStack(null);
    ft.commit();
}

If I change MainActivity extends AppCompatActivity to MainActivity extends Activity the problem goes away and I am able to go backwards through my fragments.

Changing calls to getFragmentManager() to getSupportFragmentManager() results in devices running Android < 5.0 losing the Material theme, which was the main reason for implementing AppCompatActivity in the first place.

The style referenced in my manifest <application android:theme="@style/AppTheme">

<style name="AppTheme" parent="Theme.AppCompat.Light">
    <item name="colorPrimary">@color/primary_material_light</item>
    <item name="colorPrimaryDark">@color/primary_dark_material_light</item>
    <item name="colorAccent">@color/accent_material_light</item>
</style>

Answer 1

I was able to resolve this by overriding onBackPressed() in my Activity:

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() > 0) {
        getFragmentManager().popBackStack();
    } else {
        super.onBackPressed();
    }
}

If anybody has any insight into why this extra step is necessary when using AppCompatActivity I would be interested to know.

Answer 2

use getSupportFragmentManager() instead of getFragmentManager()