zulu15

package com.zulu.fireapp;

import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ListView;
import android.widget.TextView;
import com.firebase.ui.database.FirebaseListAdapter;

EduardoSP6

# In this situation I have the MainActivity that calls FragmentA. This fragment implements OnBackStackChangedListener, 
# and checks the size of the backStack; if it's less than one, then it hides the UP button. The fragments B and C are called by
# the A, them just show/hide the button.

# MainActivity:

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home: