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{

		@Override
		public void onClick(View arg0) {
			// TODO Auto-generated method stub
			Message msg=handler.obtainMessage();
			msg.what=2;
			handler.sendMessage(msg);
		}
    	
    }
    class FirstHandler extends Handler{

		@Override
		public 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。