Android实现计时与倒计时的常用方法小结

本文实例总结了Android实现计时与倒计时的常用方法。分享给大家供大家参考，具体如下：

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

希望本文所述对大家Android程序设计有所帮助。