android基础学习 菜单optionMenu

1.选项菜单（optionMenu）

    创建选项菜单的步骤：

     1.覆盖Activity的 onCreateOptionMenu(Menu menu)方法，当菜单第一次被打开时调用

     2.调用Menu的add() 方法添加菜单项（MenuItem）,同时可以调用MenuItem的setlcon()方法为菜单项设置图标

     3.当菜单项（MenuItem）被选择是，覆盖Activity 的onOptionsItemSelected(MenuItem item)来响应事件

import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.view.MenuItem;import android.view.SubMenu;import android.widget.Toast;public class MainActivity extends Activity {private static final int SET_ITEM1=Menu.FIRST+2;private static final int SET_ITEM2=Menu.FIRST+3;private static final int SET_ITEM3=Menu.FIRST+4;private static final int SET_ITEM4=Menu.FIRST+5;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);}//填充选项菜单（读取xml文件，解析，加载到Menu组件上）@Overridepublic boolean onCreateOptionsMenu(Menu menu) {getMenuInflater().inflate(R.menu.main, menu);  //添加子菜单SubMenu sub1=menu.addSubMenu("设置");sub1.add(1,SET_ITEM1,300,"设置声音");sub1.add(1,SET_ITEM2,400,"设置桌面");SubMenu sub2=menu.addSubMenu("选择");sub2.add(1,SET_ITEM3,300,"选择一");sub2.add(1,SET_ITEM4,400,"选择二");return true;}@Overridepublic boolean onOptionsItemSelected(MenuItem item){switch(item.getItemId()){case R.id.start:Toast.makeText(this, "开始游戏", Toast.LENGTH_SHORT).show();break;case R.id.over:Toast.makeText(this, "结束游戏", Toast.LENGTH_SHORT).show();break;case SET_ITEM1:Toast.makeText(this,"声音设置" , Toast.LENGTH_SHORT).show();break;case SET_ITEM2:Toast.makeText(this, "桌面设置", Toast.LENGTH_SHORT).show();break;case SET_ITEM3:Toast.makeText(this, "选择一", Toast.LENGTH_SHORT).show();break;case SET_ITEM4:Toast.makeText(this, "选择二", Toast.LENGTH_SHORT).show();break;default:break;}return super.onOptionsItemSelected(item);}}

在res文件夹下，values文件下的Strings.xml 

<?xml version="1.0" encoding="utf-8"?><resources>    <string name="app_name">游戏</string>    <string name="start">开始</string>    <string name="over">结束</string>       <string name="hello_world">你好世界！</string>    <string name="contextTitle">上下文菜单</string></resources>