BottomNavgation

 1.ActivityMain.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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <FrameLayout
        android:id="@+id/fram"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginBottom="?actionBarSize" />


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



</RelativeLayout>

2.res> menu . Xml

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

    <item android:id="@+id/hnev"
        android:icon="@drawable/ic_baseline_home_24"
        android:title="home" />
    <item android:id="@+id/gnev"
        android:icon="@drawable/image24"
        android:title="gallery"/>

    <item android:id="@+id/callnev"
        android:icon="@drawable/call24"
        android:title="call"/>
</menu>

3.photo go to Drawble > Vector Asst

4.

package abhiandroid.com.prectice;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;

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

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

public class MainActivity extends AppCompatActivity {

    BottomNavigationView nev;

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

        nev = findViewById(R.id.nev);

        nev.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {

                int id = item.getItemId();
                if(id == R.id.hnev ){

                    FragmentManager fragmentManager = getSupportFragmentManager();

                    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

                    fragmentTransaction.add(R.id.fram,new BlankFragment());

                    fragmentTransaction.commit();

                }else if (id == R.id.gnev ){

                    FragmentManager fragmentManager = getSupportFragmentManager();

                    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

                    fragmentTransaction.add(R.id.fram,new BlankFragment2());
                    fragmentTransaction.commit();


                }else {
                    FragmentManager fragmentManager = getSupportFragmentManager();

                    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

                    fragmentTransaction.add(R.id.fram,new BlankFragment3());

                    fragmentTransaction.commit();


                }


                return true; // light cheng
            }
        });



    }
}

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