Android实现计时与倒计时的几种方法

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() {
         @Override
         public void run() {

             runOnUiThread(new Runnable() {      // UI thread
                 @Override
                 public 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(){
         @Override
         public 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() {
         @Override
         public 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);     // Message
         handler.sendMessageDelayed(message, 1000);
     }

     final Handler handler = new Handler(){

         public void handleMessage(Message msg){         // handle message
             switch (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(){          // handle
         public void handleMessage(Message msg){
             switch (msg.what) {
             case 1:
                 recLen++;
                 txtView.setText("" + recLen);
             }
             super.handleMessage(msg);
         }
     };

     public class MyThread implements Runnable{      // thread
         @Override
         public void run(){
             while(true){
                 try{
                     Thread.sleep(1000);     // sleep 1000ms
                     Message 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() {
         @Override
         public 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 

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() {
         @Override
         public void run() {

             runOnUiThread(new Runnable() {      // UI thread
                 @Override
                 public 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(){
         @Override
         public 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() {
         @Override
         public 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);     // Message
         handler.sendMessageDelayed(message, 1000);
     }

     final Handler handler = new Handler(){

         public void handleMessage(Message msg){         // handle message
             switch (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(){          // handle
         public void handleMessage(Message msg){
             switch (msg.what) {
             case 1:
                 recLen++;
                 txtView.setText("" + recLen);
             }
             super.handleMessage(msg);
         }
     };

     public class MyThread implements Runnable{      // thread
         @Override
         public void run(){
             while(true){
                 try{
                     Thread.sleep(1000);     // sleep 1000ms
                     Message 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() {
         @Override
         public 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