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Question

I have an AppCompatActivity with

        Android.Support.V7.Widget.Toolbar myToolbar = (Android.Support.V7.Widget.Toolbar)FindViewById(Resource.Id.my_toolbar);
        SetSupportActionBar(myToolbar);
        SupportActionBar.SetDisplayHomeAsUpEnabled(true);

I use fragments in this activity to change what is displayed under the toolbar. I want each fragment (on SupportFragmentManager.BeginTransaction().Replace(Resource.Id.content, myFragment).Commit() ) to be pushed on a stack so on toolbar back button touch or android back button press previous fragment is popped and displayed. How to do that?

Answer 1

I solved that by overriding OnOptionsItemSelected in my activity:

    public override bool OnOptionsItemSelected(IMenuItem item)
    {
        if (SupportFragmentManager.BackStackEntryCount == 0)
        {
            return base.OnOptionsItemSelected(item);
        }

        SupportFragmentManager.PopBackStack();
        return true;
    }

Note: No need to override OnBackPressed.

Answer 2

use this :

    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    fragmentTransaction.replace(containerId, fragment, fragment.getClass().getSimpleName());
    fragmentTransaction.addToBackStack(null);
    fragmentTransaction.commit();

@Override
public void onBackPressed() { //or use on menu item clicked
    FragmentManager fragmentManager = getSupportFragmentManager();
    if (fragmentManager.getBackStackEntryCount() > 0) {
        fragmentManager.popBackStack();
    }else {
        super.onBackPressed();
    }
}