Handler1

private Button button;private Handler handler;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        button=(Button)findViewById(R.id.buttonId);        handler=new FirstHandler();    }    class ButtonListener implements OnClickListener{@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubMessage msg=handler.obtainMessage();msg.what=2;handler.sendMessage(msg);}        }    class FirstHandler extends Handler{@Overridepublic void handleMessage(Message msg) {int what=msg.what;System.out.println(what);}        }

以上为主要代码，在控制台输出数字2。