How to go back to previous fragment from activity?

Question

I've got an app with nav drawer, which is switching fragments. From inside one of those fragments, I am calling a new activity. When I click back in this activity (in toolbar), I want to go back to previous selected fragment but instead it puts me back to first fragment. I am adding my fragment to back stack so this should not be a problem.

Here is what I have already tried:

I have overriden the onBackPressed method in my 2nd activity like this:

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() == 0) {
        this.finish();
    } else {
        getFragmentManager().popBackStack();
    }
}

It is not working. I also saved index of current fragment inside onsaveinstancestate method and retrieve it but same result. I also tried with always putting current fragment inside variable and try to reshow it but still, it does not work. Anything else I could try?

Fun fact: if I press back inside bottom panel, it does actually goes back to previous fragment.

EDIT: Here is my code for doing this:

 private void replaceFragment(Fragment fragment)
 {
     if (fragment != null)
     {
         FragmentManager manager = getSupportFragmentManager();
         manager.beginTransaction()
                    .replace(R.id.main_content, fragment)
                    .addToBackStack(null)
                    .commit();
        }
    }

I add first fragment only, if savedInstanceState is null, like so:

if (savedInstanceState == null) {
    // first time
    mTitle = getResources().getString(R.string.home);
    replaceFragment(HomeFragment.newInstance()); 
}

And yes, all this is done inside onCreate() method.

Answer 1

I had the same problem and got fixed. The only thing you need to do is to override the method "onOptionsItemSelected" in the activity:

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId() == android.R.id.home) {
        finish();
        return true;
    }
    return super.onOptionsItemSelected(item);
}

android.R.id.home is your first fragment in the menu.

Answer 2

What I tend to do is this

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() == 0) {
        this.finish();
    } else {
        super.onBackPressed(); //replaced
    }
}

This way it handles the fragment stuff on its own within, but when there's no fragments left to go back to, then it finishes the activity.

EDIT: UP navigation can recreate your previous activity even if it already exists. To prevent that from happening, redefine the Up navigation's event in onOptionsItemSelected like so:

public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
            Intent parentIntent = NavUtils.getParentActivityIntent(this);
            if(parentIntent == null) { 
                finish();
                return true;
            } else {
                parentIntent.setFlags(Intent.FLAG_ACTIVITY_BROUGHT_TO_FRONT | Intent.FLAG_ACTIVITY_SINGLE_TOP | Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                startActivity(parentIntent);
                finish();
                return true;
            }
    }
    return super.onOptionsItemSelected(item);
}