MainActivity.java bottomnavigationbar

package com.example.saigopinarimeti.helloworld;

import android.app.ProgressDialog;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v4.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    BottomNavigationView bottomNavigationView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bottomNavigationView = findViewById(R.id.bottomNavigationBar);

        // to load default fragment
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.beginTransaction().add(R.id.frameLayout,new HomeFragment()).commit();

        bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.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()).commit();
                }
                if (menuItem.getItemId() == R.id.trending){
                    Toast.makeText(MainActivity.this, "trending", Toast.LENGTH_SHORT).show();
                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().add(R.id.frameLayout,new TrendingFragment()).commit();

                }
                if (menuItem.getItemId() == R.id.sub){
                    Toast.makeText(MainActivity.this, "sub", Toast.LENGTH_SHORT).show();
                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().add(R.id.frameLayout,new SubscriptionFragment()).commit();
                }
                if (menuItem.getItemId() == R.id.inbox){
                    Toast.makeText(MainActivity.this, "inbox", Toast.LENGTH_SHORT).show();
                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().add(R.id.frameLayout,new INboxFragment()).commit();
                }
                if (menuItem.getItemId() == R.id.library){
                    Toast.makeText(MainActivity.this, "library", Toast.LENGTH_SHORT).show();
                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().add(R.id.frameLayout,new LibraryFragment()).commit();
                }
                return true;
            }
        });

    }
}