android 实现倒计时和计时的5种方法

来源：互联网发布：如何练形体气质知乎编辑：程序博客网时间：2024/05/20 17:26

第一种 Timer与TimerTask（Java实现）

publicclass timerTask extendsActivity{ 
  
    privateint recLen = 11; 
    privateTextView txtView; 
    Timer timer = newTimer(); 
  
    publicvoid onCreate(Bundle savedInstanceState){ 
        super.onCreate(savedInstanceState); 
           
        setContentView(R.layout.timertask); 
        txtView = (TextView)findViewById(R.id.txttime); 
           
        timer.schedule(task, 1000, 1000);       // timeTask 
    }    
  
    TimerTask task = newTimerTask() { 
        @Override 
        publicvoid run() { 
  
            runOnUiThread(newRunnable() {      // UI thread 
                @Override 
                publicvoid 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）

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publicclasstimerTask extendsActivity{ 
    privateintrecLen = 11; 
    privateTextView txtView; 
    Timer timer = newTimer(); 
  
    publicvoidonCreate(Bundle savedInstanceState){ 
        super.onCreate(savedInstanceState); 
  
        setContentView(R.layout.timertask); 
        txtView = (TextView)findViewById(R.id.txttime); 
  
        timer.schedule(task, 1000, 1000);       // timeTask 
    }    
  
    finalHandler handler = newHandler(){ 
        @Override 
        publicvoidhandleMessage(Message msg){ 
            switch(msg.what) { 
            case1: 
                txtView.setText(""+recLen); 
                if(recLen < 0){ 
                    timer.cancel(); 
                    txtView.setVisibility(View.GONE); 
                } 
            } 
        } 
    }; 
  
    TimerTask task = newTimerTask() { 
        @Override 
        publicvoidrun() { 
            recLen--; 
            Message message = newMessage(); 
            message.what = 1; 
            handler.sendMessage(message); 
        } 
    }; 
}

方法三

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Handler与Message（不用TimerTask）
 
publicclasstimerTask extendsActivity{ 
    privateintrecLen = 11; 
    privateTextView txtView; 
  
    publicvoidonCreate(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); 
    }   
  
    finalHandler handler = newHandler(){ 
  
        publicvoidhandleMessage(Message msg){         // handle message 
            switch(msg.what) { 
            case1: 
                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）

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publicclasstimerTask extendsActivity{ 
    privateintrecLen = 0; 
    privateTextView txtView; 
  
    publicvoidonCreate(Bundle savedInstanceState){ 
        super.onCreate(savedInstanceState); 
  
        setContentView(R.layout.timertask); 
        txtView = (TextView)findViewById(R.id.txttime); 
           
        newThread(newMyThread()).start();         // start thread 
    }    
  
    finalHandler handler = newHandler(){          // handle 
        publicvoidhandleMessage(Message msg){ 
            switch(msg.what) { 
            case1: 
                recLen++; 
                txtView.setText(""+ recLen); 
            } 
            super.handleMessage(msg); 
        } 
    }; 
  
    publicclassMyThread implementsRunnable{      // thread 
        @Override 
        publicvoidrun(){ 
            while(true){ 
                try{ 
                    Thread.sleep(1000);     // sleep 1000ms 
                    Message message = newMessage(); 
                    message.what = 1; 
                    handler.sendMessage(message); 
                }catch(Exception e) { 
                } 

方法五

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Handler与Runnable（最简单型） 
 
publicclasstimerTask extendsActivity{ 
    privateintrecLen = 0; 
    privateTextView txtView; 
  
    publicvoidonCreate(Bundle savedInstanceState){ 
        super.onCreate(savedInstanceState); 
  
        setContentView(R.layout.timertask); 
        txtView = (TextView)findViewById(R.id.txttime); 
           
        handler.postDelayed(runnable, 1000); 
    }    
  
    Handler handler = newHandler(); 
    Runnable runnable = newRunnable() { 
        @Override 
        publicvoidrun() { 
            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

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