Android异步消息处理机制

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    public static final int UPDATE_TEXT = 1;
    private TextView text;
    private Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what) {
                case UPDATE_TEXT:
                    text.setText("Nice to meet you");
                    break;
                default:
                    break;
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        text = (TextView) findViewById(R.id.text);
        Button changeText = (Button) findViewById(R.id.change_text);
        changeText.setOnClickListener(this);
     }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.change_text:
                new Thread(new Runnable() {
                    @Override
                    public void run() {
                        Message message = new Message();
                        message.what = UPDATE_TEXT;
                        handler.sendMessage(message);
                    }
                }).start();
                break;
            default:
                break;
        }
    }
}