Android 计时与倒计时

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