Menu in Android

 It is used to provide navigation on Android Application

OptionMenuActivity.Java 

package com.example.customdrawer;

import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

public class OptionMenuActivity extends AppCompatActivity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.home) {
            Toast.makeText(getApplicationContext(),"home",Toast.LENGTH_LONG).show();
        }
       else if (id == R.id.about) {
            Toast.makeText(getApplicationContext(),"about us",Toast.LENGTH_LONG).show();
        }
        else if (id == R.id.contact) {
            Toast.makeText(getApplicationContext(),"contact us",Toast.LENGTH_LONG).show();
        }
        return super.onOptionsItemSelected(item);
    }
}

menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu 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"
    tools:context="com.example.myapplication.MainActivity">
    <item
        android:id="@+id/home"
        android:orderInCategory="100"
        android:title="HOME"
        app:showAsAction="never" />

    <item
        android:id="@+id/about"
        android:orderInCategory="100"
        android:title="About US"
        app:showAsAction="never" />

    <item
        android:id="@+id/contact"
        android:orderInCategory="100"
        android:title="Contact US"
        app:showAsAction="never" />
</menu>

POPUPMENU:-

package com.example.customdrawer;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.PopupMenu;
import android.widget.Toast;

public class Popupmenuactivity extends AppCompatActivity {

    Button btn;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_popupmenuactivity);
        btn = findViewById(R.id.btnpopmenu);
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                PopupMenu popup = new PopupMenu(Popupmenuactivity.this, btn);
                popup.getMenuInflater().inflate(R.menu.menu, popup.getMenu());
                popup.show();
                popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                    @Override
                    public boolean onMenuItemClick(MenuItem item) {
                                             Toast.makeText(getApplicationContext(),"You Clicked : " + item.getTitle(), Toast.LENGTH_SHORT).show();
                                              return true;

                    }
                });
            }
        });

    }
}

XML FILE:-
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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=".Popupmenuactivity">
    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btnpopmenu"
        android:text="Click"></Button>

</LinearLayout>

Menu.xml
<?xml version="1.0" encoding="utf-8"?>
<menu 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"
    tools:context="com.example.myapplication.MainActivity">
    <item
        android:id="@+id/home"
        android:orderInCategory="100"
        android:title="HOME"
        app:showAsAction="never" />

    <item
        android:id="@+id/about"
        android:orderInCategory="100"
        android:title="About US"
        app:showAsAction="never" />

    <item
        android:id="@+id/contact"
        android:orderInCategory="100"
        android:title="Contact US"
        app:showAsAction="never" />
</menu>