Create Dynamically Popup Menu in Android

Create new project in Android Studio with steps as below:

Open res\values\strings.xml file and add new string as below:

<resources>
    <string name="app_name">Learn Android with Real Apps</string>
    <string name="show_popup_menu">Show Popup Menu</string>
    <string name="menu1">Menu 1</string>
    <string name="menu2">Menu 2</string>
    <string name="menu3">Menu 3</string>
    <string name="menu3_1">Menu 3.1</string>
    <string name="menu3_2">Menu 3.2</string>
</resources>

Open res\layout\activity_main.xml file and create layout as below:

<?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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/buttonPopupMenu"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="@string/show_popup_menu" />

</LinearLayout>

Add code to MainActivity.java in android.demo.learnandroidwithrealapps package as below:

package android.demo.learnandroidwithrealapps;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.PopupMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.SubMenu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private static final int MENU1 = 0;
    private static final int MENU2 = 1;
    private static final int MENU3 = 2;

    private static final int MENU_1_ITEM = Menu.FIRST;
    private static final int MENU_2_ITEM = Menu.FIRST + 1;
    private static final int MENU_3_ITEM = Menu.FIRST + 2;
    private static final int MENU_3_1_ITEM = MENU_3_ITEM + 1;
    private static final int MENU_3_2_ITEM = MENU_3_ITEM + 2;

    private Button buttonPopupMenu;

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

    private void initView() {
        buttonPopupMenu = findViewById(R.id.buttonPopupMenu);
        buttonPopupMenu.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                buttonPopupMenu_onClick(view);
            }
        });
    }

    private void buttonPopupMenu_onClick(View view) {
        PopupMenu popupMenu = new PopupMenu(MainActivity.this, buttonPopupMenu);
        popupMenu.getMenu().add(MENU1, MENU_1_ITEM, 0, getText(R.string.menu1));
        popupMenu.getMenu().add(MENU2, MENU_2_ITEM, 1, getText(R.string.menu2));
        SubMenu menu3 = popupMenu.getMenu().addSubMenu(MENU3, MENU_3_ITEM, 2, getText(R.string.menu3));
        menu3.add(MENU3, MENU_3_1_ITEM, 0, getText(R.string.menu3_1));
        menu3.add(MENU3, MENU_3_2_ITEM, 1, getText(R.string.menu3_2));
        popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
            @Override
            public boolean onMenuItemClick(MenuItem item) {
                Toast.makeText(MainActivity.this, item.getTitle(), Toast.LENGTH_SHORT).show();
                return false;
            }
        });
        popupMenu.show();
    }

}