方法一
Timer与TimerTask（Java实现）
public class timerTask extends Activity{private int recLen = 11;private TextView txtView;Timer timer = new Timer();public void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.timertask);txtView = (TextView)findViewById(R.id.txttime);timer.schedule(task, 1000, 1000);// timeTask}TimerTask task = new TimerTask() {@Overridepublic void run() {runOnUiThread(new Runnable() {// UI thread@Overridepublic void run() {recLen–;txtView.setText(""+recLen);if(recLen < 0){timer.cancel();txtView.setVisibility(View.GONE);}}});}};}
方法二
TimerTask与Handler（不用Timer的改进型）
public class timerTask extends Activity{private int recLen = 11;private TextView txtView;Timer timer = new Timer();public void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.timertask);txtView = (TextView)findViewById(R.id.txttime);timer.schedule(task, 1000, 1000);// timeTask}final Handler handler = new Handler(){@Overridepublic void handleMessage(Message msg){switch (msg.what) {case 1:txtView.setText(""+recLen);if(recLen < 0){timer.cancel();txtView.setVisibility(View.GONE);}}}};TimerTask task = new TimerTask() {@Overridepublic void run() {recLen–;Message message = new Message();message.what = 1;handler.sendMessage(message);}};}方法三
Handler与Message（不用TimerTask）
public class timerTask extends Activity{private int recLen = 11;private TextView txtView;public void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.timertask); txtView = (TextView)findViewById(R.id.txttime);Message message = handler.obtainMessage(1);// Messagehandler.sendMessageDelayed(message, 1000);}final Handler handler = new Handler(){public void handleMessage(Message msg){// handle messageswitch (msg.what) {case 1:recLen–;txtView.setText("" + recLen);if(recLen > 0){Message message = handler.obtainMessage(1);handler.sendMessageDelayed(message, 1000);// send message}else{txtView.setVisibility(View.GONE);}}super.handleMessage(msg);}};}方法四
Handler与Thread（不占用UI线程）
public class timerTask extends Activity{private int recLen = 0;private TextView txtView;public void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.timertask);txtView = (TextView)findViewById(R.id.txttime);new Thread(new MyThread()).start();// start thread}final Handler handler = new Handler(){// handlepublic void handleMessage(Message msg){switch (msg.what) {case 1:recLen++;txtView.setText("" + recLen);}super.handleMessage(msg);}};public class MyThread implements Runnable{// thread@Overridepublic void run(){while(true){try{Thread.sleep(1000);// sleep 1000msMessage message = new Message();message.what = 1;handler.sendMessage(message);}catch (Exception e) {}}}}}方法五
Handler与Runnable（最简单型）
public class timerTask extends Activity{private int recLen = 0;private TextView txtView;public void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.timertask);txtView = (TextView)findViewById(R.id.txttime);handler.postDelayed(runnable, 1000);}Handler handler = new Handler();Runnable runnable = new Runnable() {@Overridepublic void run() {recLen++;txtView.setText("" + recLen);handler.postDelayed(this, 1000);}};}
计时与倒计时
方法1，方法2和方法3，都是倒计时
方法4，方法5，都是计时
计时和倒计时，都可使用上述方法实现（代码稍加改动）
UI线程比较
方法1，方法2和方法3，都是在UI线程实现的计时；
方法4和方法5，是另开Runnable线程实现计时
实现方式比较
方法1，采用的是Java实现，即Timer和TimerTask方式；
其它四种方法，都采用了Handler消息处理
推荐使用
如果对UI线程交互要求不很高，可以选择方法2和方法3
如果考虑到UI线程阻塞，，严重影响到用户体验，推荐使用方法4，另起线程单独用于计时和其它的逻辑处理
方法5，综合了前几种方法的优点，是最简的
参考推荐：
Android之多线程工作-AsyncTask与handler
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