Android创建一个选项菜单

package com.example.menu;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

/**
* 创建一个选项菜单
* 1.在res目录下创建一个menu文件夹
* 2.在menu文件夹下创建一个main.xml菜单文件
* 3.MainActivity中重写onCreateOptionsMenu()方法和onOptionsItemSelected()方法
* 4.程序运行之后右上角有三个点,可以点击
*/
public class MainActivity extends AppCompatActivity {

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

// 创建一个选项菜单
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.main, menu);
// You must return true for the menu to be displayed; if you return false it will not be shown.
return true;
}

// 为选项菜单添加响应事件
@Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case R.id.add_item:
Toast.makeText(this, "点击了Add选项", Toast.LENGTH_SHORT).show();
break;
case R.id.remove_item:
Toast.makeText(this, "点击了Remove选项", Toast.LENGTH_SHORT).show();
break;
}
return super.onOptionsItemSelected(item);
}
}

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

<item
android:id="@+id/remove_item"
android:title="Remove" />

</menu>