코딩도상국

1. Create Option menu 

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

</menu>

2. Create Menu Item 

test_menu.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/test_1"
        android:title="Test1">
    </item>

    <item
        android:id="@+id/test_2"
        android:title="Test2">
    </item>

    <item
        android:id="@+id/test_3"
        android:title="Test3">
    </item>
</menu>

MainActivity.java

onCreate OptionsMenu method 생성  ( 직접 작성해도 됨 )

ackage com.example.project7_optionmenu;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.Menu;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
	
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        return super.onCreateOptionsMenu(menu);
    }
}

코드 추가 ( xml, java 연결 )

...
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
		
        // 코드 추가
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.test_menu, menu);
		//
        return super.onCreateOptionsMenu(menu);
    }
...

2. Event 

...
    // option menu event method
    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        switch(item.getItemId())
        {
            case R.id.test_1:
                Toast.makeText(getApplicationContext(), "Test1", Toast.LENGTH_LONG).show();
            case R.id.test_2:
                Toast.makeText(getApplicationContext(), "Test2", Toast.LENGTH_LONG).show();
            case R.id.test_3:
                Toast.makeText(getApplicationContext(), "Test3", Toast.LENGTH_LONG).show();
        }

        return super.onOptionsItemSelected(item);
    }
    ...

full main java code 

package com.example.project7_optionmenu;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

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

public class MainActivity extends AppCompatActivity {

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.test_menu, menu);

        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
        switch(item.getItemId())
        {
            case R.id.test_1:
                Toast.makeText(getApplicationContext(), "Test1", Toast.LENGTH_LONG).show();
            case R.id.test_2:
                Toast.makeText(getApplicationContext(), "Test2", Toast.LENGTH_LONG).show();
            case R.id.test_3:
                Toast.makeText(getApplicationContext(), "Test3", Toast.LENGTH_LONG).show();
        }

        return super.onOptionsItemSelected(item);
    }
}

developer.android.com/guide/topics/ui/menus?hl=ko