Android計時與倒計時的幾種方法

方法一

Timer與TimerTask（Java實現）

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);
                    }
                }
            });
        }
    };
}

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與Handler（不用Timer的改進型）

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);
        }
    };
}

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與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);
        }
    };
}

Handler與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與Thread（不佔用UI線程）

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) {
                }

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與Runnable（最簡單型）

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);
        }
    };
}

Handler與Runnable（最簡單型）  

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);  
        }  
    };  
}  

計時與倒計時 
方法1，方法2和方法3，都是倒計時 
方法4，方法5，都是計時 
計時和倒計時，都可使用上述方法實現（代碼稍加改動） 

UI線程比較 
方法1，方法2和方法3，都是在UI線程實現的計時； 
方法4和方法5，是另開Runnable線程實現計時 

實現方式比較 
方法1，採用的是Java實現，即Timer和TimerTask方式； 
其它四種方法，都採用了Handler消息處理 

推薦使用 
如果對UI線程交互要求不很高，可以選擇方法2和方法3 
如果考慮到UI線程阻塞，嚴重影響到用戶體驗，推薦使用方法4，另起線程單獨用於計時和其它的邏輯處理 
方法5，綜合了前幾種方法的優點，是最簡的