Hướng dẫn và ví dụ Android PopupMenu

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    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">

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="16dp"
        android:text="Check Me"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="PopupMenu will anchor on me"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button1" />
</androidx.constraintlayout.widget.ConstraintLayout>

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/menuItem_upload"
        android:icon="@drawable/icon_upload"
        android:title="Upload" />
    <item
        android:id="@+id/menuItem_bookmark"
        android:icon="@drawable/icon_bookmark"
        android:title="Bookmark" />
    <item
        android:id="@+id/menuItem_share"
        android:icon="@drawable/icon_share"
        android:title="Share">
        <menu>
            <item
                android:id="@+id/menuItem_facebook"
                android:title="Facebook" />
            <item
                android:id="@+id/menuItem_instagram"
                android:title="Instagram" />
        </menu>
    </item>
</menu>

package org.o7planning.popupmenuexample;

import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity  {

    public static final String LOG_TAG =  "PopupMenuExample";

    private Button button1;
    private Button button2;

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

        this.button1 = (Button) findViewById(R.id.button1);
        this.button2 = (Button) findViewById(R.id.button2);

        this.button1.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                button1Clicked( );
            }
        });
    }

    // User click on the Button 1.
    private void button1Clicked( )  {
        // When user click on the Button 1, create a PopupMenu.
        // And anchor Popup to the Button 2.
        PopupMenu popup = new PopupMenu(this, this.button2);
        popup.inflate(R.menu.layout_popup_menu);

        Menu menu = popup.getMenu();
        // com.android.internal.view.menu.MenuBuilder
        Log.i(LOG_TAG, "Menu class: " + menu.getClass().getName());

        // Register Menu Item Click event.
        popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
            @Override
            public boolean onMenuItemClick(MenuItem item) {
                return menuItemClicked(item);
            }
        });

        // Show the PopupMenu.
        popup.show();
    }

    // When user click on Menu Item.
    // @return true if event was handled.
    private boolean menuItemClicked(MenuItem item) {
        switch (item.getItemId()) {
            case R.id.menuItem_bookmark:
                Toast.makeText(this, "Bookmark", Toast.LENGTH_SHORT).show();
                break;
            case R.id.menuItem_upload:
                Toast.makeText(this, "Upload", Toast.LENGTH_SHORT).show();
                break;
            case R.id.menuItem_facebook:
                Toast.makeText(this, "Share Facebook", Toast.LENGTH_SHORT).show();
                break;
            case R.id.menuItem_instagram:
                Toast.makeText(this, "Share Instagram", Toast.LENGTH_SHORT).show();
                break;
            default:
                Toast.makeText(this, item.getTitle(), Toast.LENGTH_SHORT).show();
                break;
        }
        return true;
    }
}

// Create a PopupMenu using Java.
public void createPopupMenu(Context activity, View anchorView ) {
    // Create a PopupMenu and anchor it on a View.
    PopupMenu popupMenu = new PopupMenu(activity, anchorView);

    Menu menu = popupMenu.getMenu();

    // groupId, itemId, order, title
    MenuItem menuItemUpload = menu.add(1, 1, 1, "Upload");
    MenuItem menuItemBookmark = menu.add(2, 2, 2, "Bookmark");
    menuItemUpload.setIcon(R.drawable.icon_upload);
    menuItemBookmark.setIcon(R.drawable.icon_bookmark);

    // groupId, itemId, order, title
    SubMenu subMenuShare=  menu.addSubMenu(3, 3, 3, "Share");
    subMenuShare.setIcon(R.drawable.icon_share);

    subMenuShare.add(4, 31, 1, "Google" );
    subMenuShare.add(5, 32, 2, "Instagram");
}