Android中Handler的使用
Handler主要接受子public class TestActivity extends Activity {private int count = 1;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);new Thread(new TitleThread()).start();}class TitleThread implements Runnable {@Overridepublic void run() {while (true) {setTitle("Welcome to my blog" + count++);try {Thread.sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}}}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {getMenuInflater().inflate(R.menu.activity_main, menu);return true;}}然而当我们执行程序，并不能达到我们预期的效果，所以Android 引进了Handler 这个特殊的类，可以说它是Runnable和Activity交互的桥梁，所以我们只要在run方法中发送Message,而在Handler里，通过不同的Message执行不同的任务。所以我们修改后的代码如下:
public class MainActivity extends Activity {private int count = 1; private Handler handler=new Handler(){ public void handleMessage(android.os.Message msg) { switch (msg.what) {case 1:updateTitle();break;default:break;} } };@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);new Thread(new TitleThread()).start();}protected void updateTitle() {setTitle("Welcome to my blog" + count++);}class TitleThread implements Runnable {@Overridepublic void run() {while (true) {Message message=new Message();message.what=1;handler.sendMessage(message);try {Thread.sleep(5000);} catch (InterruptedException e) {e.printStackTrace();}}}}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {getMenuInflater().inflate(R.menu.activity_main, menu);return true;}}public class TimerActivity extends Activity {private int count = 1; private Handler handler=new Handler(){ public void handleMessage(android.os.Message msg) { switch (msg.what) {case 1:updateTitle();break;default:break;} } };@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);Timer timer=new Timer();timer.scheduleAtFixedRate(new TimerTask() {@Overridepublic void run() {Message message=new Message();message.what=1;handler.sendMessage(message);}}, 1000,5000);}protected void updateTitle() {setTitle("Welcome to my blog" + count++);}}