public class LooperDemoActivity extends Activity {
??? private WorkerThread mWorkerThread;
??? private TextView mStatusLine;
??? private Handler mMainHandler;

??? @Override
??? public void onCreate(Bundle icicle) {
?super.onCreate(icicle);
?setContentView(R.layout.looper_demo_activity);
?mMainHandler = new Handler() {
???? @Override
???? public void handleMessage(Message msg) {
??String text = (String) msg.obj;
??if (TextUtils.isEmpty(text)) {
????? return;
??}
??mStatusLine.setText(text);
???? }
?};

?mWorkerThread = new WorkerThread();
?final Button action = (Button) findViewById(R.id.looper_demo_action);
?action.setOnClickListener(new View.OnClickListener() {
???? public void onClick(View v) {
??mWorkerThread.executeTask("please do me a favor");
???? }
?});
?final Button end = (Button) findViewById(R.id.looper_demo_quit);
?end.setOnClickListener(new View.OnClickListener() {
???? public void onClick(View v) {
??mWorkerThread.exit();
???? }
?});
?mStatusLine = (TextView) findViewById(R.id.looper_demo_displayer);
?mStatusLine.setText("Press 'do me a favor' to execute a task, press 'end of service' to stop looper thread");
??? }

??? @Override
??? public void onDestroy() {
?super.onDestroy();
?mWorkerThread.exit();
?mWorkerThread = null;
??? }

??? private class WorkerThread extends Thread {
?protected static final String TAG = "WorkerThread";
?private Handler mHandler;
?private Looper mLooper;

?public WorkerThread() {
???? start();
?}

?public void run() {
???? // Attention: if you obtain looper before Looper#prepare(), you can still use the looper
???? // to process message even after you call Looper#quit(), which means the looper does not
???? //really quit.
???? Looper.prepare();
???? // So we should call Looper#myLooper() after Looper#prepare(). Anyway, we should put all stuff between Looper#prepare()
???? // and Looper#loop().
???? // In this case, you will receive "Handler{4051e4a0} sending message to a Handler on a dead thread
???? // 05-09 08:37:52.118: W/MessageQueue(436): java.lang.RuntimeException: Handler{4051e4a0} sending message
???? // to a Handler on a dead thread", when try to send a message to a looper which Looper#quit() had called,
???? // because the thread attaching the Looper and Handler dies once Looper#quit() gets called.
???? mLooper = Looper.myLooper();
???? // either new Handler() and new Handler(mLooper) will work
???? mHandler = new Handler(mLooper) {
??@Override
??public void handleMessage(Message msg) {
????? /*
?????? * Attention: object Message is not reusable, you must obtain a new one for each time you want to use it.
?????? * Otherwise you got "android.util.AndroidRuntimeException: { what=1000 when=-15ms obj=it is my please
?????? * to serve you, please be patient to wait!........ } This message is already in use."
?????? */
//????? Message newMsg = Message.obtain();
????? StringBuilder sb = new StringBuilder();
????? sb.append("it is my please to serve you, please be patient to wait!/n");
????? Log.e(TAG, "workerthread, it is my please to serve you, please be patient to wait!");
????? for (int i = 1; i < 100; i++) {
???sb.append(".");
???Message newMsg = Message.obtain();
???newMsg.obj = sb.toString();
???mMainHandler.sendMessage(newMsg);
???Log.e(TAG, "workthread, working" + sb.toString());
???SystemClock.sleep(100);
????? }
????? Log.e(TAG, "workerthread, your work is done.");
????? sb.append("/nyour work is done");
????? Message newMsg = Message.obtain();
????? newMsg.obj = sb.toString();
????? mMainHandler.sendMessage(newMsg);
??}
???? };
???? Looper.loop();
?}

?public void exit() {
???? if (mLooper != null) {
??mLooper.quit();
??mLooper = null;
???? }
?}

?// This method returns immediately, it just push an Message into Thread's MessageQueue.
?// You can also call this method continuously, the task will be executed one by one in the
?// order of which they are pushed into MessageQueue(they are called).
?public void executeTask(String text) {
???? if (mLooper == null || mHandler == null) {
??Message msg = Message.obtain();
??msg.obj = "Sorry man, it is out of service";
??mMainHandler.sendMessage(msg);
??return;
???? }
???? Message msg = Message.obtain();
???? msg.obj = text;
???? mHandler.sendMessage(msg);
?}
??? }
}