MainActivity.java navigation drawer

package com.example.saigopinarimeti.helloworld;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.v4.app.FragmentManager;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Gravity;
import android.view.MenuItem;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {


    DrawerLayout drawerLayout;
    NavigationView navigationView;
    ActionBarDrawerToggle actionBarDrawerToggle;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);



        drawerLayout = findViewById(R.id.drawerLayout);
        navigationView = findViewById(R.id.navigationView);

        actionBarDrawerToggle = new ActionBarDrawerToggle(this,drawerLayout,R.string.open,R.string.close);

        drawerLayout.addDrawerListener(actionBarDrawerToggle);
        actionBarDrawerToggle.syncState();

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);


        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().add(R.id.frameLayout,new HomeFragment()).addToBackStack("sasa").commit();


        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem menuItem) {

                if (menuItem.getItemId() == R.id.home){
                    Toast.makeText(MainActivity.this, "Home", Toast.LENGTH_SHORT).show();

                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().add(R.id.frameLayout,new HomeFragment()).addToBackStack("sasa").commit();
                }

                if (menuItem.getItemId() == R.id.logout){
                    Toast.makeText(MainActivity.this, "Logout", Toast.LENGTH_SHORT).show();


                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().add(R.id.frameLayout,new LogoutFragment()).addToBackStack("sasa").commit();
                }

                if (menuItem.getItemId() == R.id.Settings){
                    Toast.makeText(MainActivity.this, "Settings", Toast.LENGTH_SHORT).show();

                    startActivity(new Intent(MainActivity.this,SettingsActivity.class));
                }

                drawerLayout.closeDrawer(Gravity.START);
                return true;
            }
        });

    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if(actionBarDrawerToggle.onOptionsItemSelected(item))
            return true;
        return super.onOptionsItemSelected(item);
    }
}