menu菜单栏的应用, 弹出对话框或退出当前activity

   public class MainActivity extends Activity {protected static final int MENU_ABOUT = Menu.FIRST;protected static final int MENU_QUIT = Menu.FIRST+1;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        Log.d(this.toString(), "you have a error");     }    @Override    //设置菜单栏的选项    public boolean onCreateOptionsMenu(Menu menu){    super.onCreateOptionsMenu(menu);        menu.add(0, MENU_ABOUT, 0, "关于");    menu.add(0, MENU_QUIT, 0, "退出");    return true;    }        @Override    //设置选项被点击后的动作    public boolean onOptionsItemSelected(MenuItem item){    super.onOptionsItemSelected(item);    switch(item.getItemId()){    //点击关于,则弹出对话框        case MENU_ABOUT:    openOptionsDialog();    break;    case MENU_QUIT:    //选择退出,则直接退出当前Activity                finish();    break;    }    return true;    }    //弹出对话框    private void openOptionsDialog(){    new AlertDialog.Builder(this).setTitle("关于JET")    .setMessage("Android Jet")    .setPositiveButton("确认", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface arg0, int arg1) {// TODO Auto-generated method stub}}).setNegativeButton("主页", new DialogInterface.OnClickListener() {@Overridepublic void onClick(DialogInterface arg0, int arg1) {// TODO Auto-generated method stubUri uri = Uri.parse("http://www.baidu.com");Intent intent = new Intent(Intent.ACTION_VIEW, uri);startActivity(intent);}})    .show();        }}