在Activity中添加选项菜单

public class MainActivity extends Activity{    private static final int ITEM1 = Menu.FIRST;    private static final int ITEM2 = Menu.FIRST+1;        public void onCreate(Bundle savedInstanceState){        super.onCreate(savedInstanceState);        setContentView(R.layout.main);   //mian是activity的界面文件        }    //重写    public boolean onCreateOptionsMenu(Menu menu){       menu.add(0,ITEM1,0,"开始");       menu.add(0,ITEM2,0,"退出");    }    public boolean onOptionsItemSelected(MenuItem item){       switch(item.getItemId()){      case ITEM1:setTitle("开始");break;case ITEM2:setTitle("退出");break;}return true;}}