Стрелка возврата из меню

/*******************MainActivity***********/
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;
import android.widget.Toast;
 
 
public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {
    private DrawerLayout drawer;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
 
        drawer= findViewById(R.id.drawer_layout);
        NavigationView navigationView=findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
 
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(this,drawer,toolbar,R.string.navigation_drawer_open,
                R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();
       /* if(savedInstanceState==null) {
            getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container, new MessageFragment()).commit();
            navigationView.setCheckedItem(R.id.nav_message);
        }*/
       
 
    }
 
    /**
     * Called when an item in the navigation menu is selected.
     *
     * @param item The selected item
     * @return true to display the item as the selected item
     */
    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch(item.getItemId()){
            case R.id.nav_message:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new MessageFragment()).commit();
 
                break;
            case R.id.nav_chat:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new ChatFragment()).commit();
 
                break;
            case R.id.nav_profile:
                getSupportFragmentManager().beginTransaction().replace(R.id.fragment_container,new ProfileFragment()).commit();
 
                break;
 
            case R.id.nav_share:
                Toast.makeText(this,"Share",Toast.LENGTH_SHORT).show();
                break;
 
            case R.id.nav_send:
                Toast.makeText(this,"Send",Toast.LENGTH_SHORT).show();
                break;
        }
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
 
    @Override
    public void onBackPressed(){
        if(drawer.isDrawerOpen(GravityCompat.START)){
            drawer.closeDrawer(GravityCompat.START);
        }else {
            super.onBackPressed();
        }
    }
 
 
}

/**************MessageFragment*****************/
package com.example.edisa.navigationdrawerexample;
 
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
 
public class MessageFragment extends Fragment {
 
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_message,container,false);
    }
}

popBackStack();