Bottom Navigation

XML 

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    
    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottomNav"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        app:menu="@menu/bottom_nav"

        />
  

</RelativeLayout>

MENU

res > new > android resource directory

resource name: menu

source name: main

menu > new > menu resource file

File Name: bottom_nav

Botton Nav

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/home"
        android:title="Home"
        android:icon="@drawable/home"
        />

    <item
        android:id="@+id/notification"
        android:title="Notification"
        android:icon="@drawable/notification"
        />

    <item
        android:id="@+id/share"
        android:title="Share"
        android:icon="@drawable/share"
        />

</menu>

JAVA

package com.rakibshah.myapplication;

import android.os.Bundle;
import android.view.MenuItem;
import android.widget.Toast;

import androidx.activity.EdgeToEdge;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.graphics.Insets;
import androidx.core.view.ViewCompat;
import androidx.core.view.WindowInsetsCompat;

import com.google.android.material.bottomnavigation.BottomNavigationView;
import com.google.android.material.navigation.NavigationBarView;

public class MainActivity extends AppCompatActivity {

    BottomNavigationView bottomNav;

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

        bottomNav = findViewById(R.id.bottomNav);

        bottomNav.getOrCreateBadge(R.id.notification).setNumber(100);


        bottomNav.setOnItemSelectedListener(new NavigationBarView.OnItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                if (item.getItemId()==R.id.home){

                    Toast.makeText(getApplicationContext(), "Home", Toast.LENGTH_LONG).show();
                }

                else if (item.getItemId()==R.id.notification){

                    Toast.makeText(getApplicationContext(), "Notification", Toast.LENGTH_LONG).show();
                }

                else if (item.getItemId()==R.id.share){

                    Toast.makeText(getApplicationContext(), "Share", Toast.LENGTH_LONG).show();
                }

                return true;
            }
        });

    }
}