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(jìn)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（不占用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) { 
        } 
      } 
    } 
  } 
}

方法五

Handler與Runnable（最簡(jiǎn)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(jì)時(shí)與倒計(jì)時(shí)

方法1，方法2和方法3，都是倒計(jì)時(shí)
方法4，方法5，都是計(jì)時(shí)
計(jì)時(shí)和倒計(jì)時(shí)，都可使用上述方法實(shí)現(xiàn)（代碼稍加改動(dòng)）

UI線程比較

方法1，方法2和方法3，都是在UI線程實(shí)現(xiàn)的計(jì)時(shí)；
方法4和方法5，是另開Runnable線程實(shí)現(xiàn)計(jì)時(shí)

實(shí)現(xiàn)方式比較

方法1，采用的是Java實(shí)現(xiàn)，即Timer和TimerTask方式；
其它四種方法，都采用了Handler消息處理

推薦使用

如果對(duì)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(yán)重影響到用戶體驗(yàn)，推薦使用方法4，另起線程單獨(dú)用于計(jì)時(shí)和其它的邏輯處理
方法5，綜合了前幾種方法的優(yōu)點(diǎn)，是最簡(jiǎn)的

希望本文所述對(duì)大家Android程序設(shè)計(jì)有所幫助。

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