android倒计时功能的实现(CountDownTimer）

 

1. new CountdownTimer(30000, 1000) { 
2.     public void onTick(long millisUntilFinished) { 
3.         mTextField.setText("seconds remaining: " + millisUntilFinished / 1000); 
4.     } 
5.     public void onFinish() { 
6.         mTextField.setText("done!"); 
7.     } 
8. }.start(); 

 new CountdownTimer(30000, 1000) {
     public void onTick(long millisUntilFinished) {
         mTextField.setText("seconds remaining: " + millisUntilFinished / 1000);
     }
     public void onFinish() {
         mTextField.setText("done!");
     }
  }.start();

 

1. package cn.demo; 
2.  
3. import android.app.Activity; 
4. import android.os.Bundle; 
5. import android.content.Intent; 
6. import android.os.CountDownTimer; 
7. import android.widget.TextView; 
8. import android.widget.Toast; 
9. public class NewActivity extends Activity { 
10.     private MyCount mc; 
11.     private TextView tv; 
12.     @Override 
13.     protected void onCreate(Bundle savedInstanceState) { 
14.         // TODO Auto-generated method stub 
15.         super.onCreate(savedInstanceState); 
16.         setContentView(R.layout.main); 
17.         tv = (TextView)findViewById(R.id.show); 
18.         mc = new MyCount(30000, 1000); 
19.         mc.start(); 
20.     }//end func 
21.  
22.     /*定义一个倒计时的内部类*/ 
23.     class MyCount extends CountDownTimer {    
24.         public MyCount(long millisInFuture, long countDownInterval) {    
25.             super(millisInFuture, countDownInterval);    
26.         }    
27.         @Override    
28.         public void onFinish() {    
29.             tv.setText("finish");       
30.         }    
31.         @Override    
32.         public void onTick(long millisUntilFinished) {    
33.             tv.setText("请等待30秒(" + millisUntilFinished / 1000 + ")...");    
34.             Toast.makeText(NewActivity.this, millisUntilFinished / 1000 + "", Toast.LENGTH_LONG).show();//toast有显示时间延迟      
35.         }   
36.     }    
37. } 

package cn.demo;

import android.app.Activity;
import android.os.Bundle;
import android.content.Intent;
import android.os.CountDownTimer;
import android.widget.TextView;
import android.widget.Toast;
public class NewActivity extends Activity {
	private MyCount mc;
	private TextView tv;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		tv = (TextView)findViewById(R.id.show);
		mc = new MyCount(30000, 1000);
		mc.start();
	}//end func

	/*定义一个倒计时的内部类*/
	class MyCount extends CountDownTimer {   
		public MyCount(long millisInFuture, long countDownInterval) {   
			super(millisInFuture, countDownInterval);   
		}   
		@Override   
		public void onFinish() {   
			tv.setText("finish");      
		}   
		@Override   
		public void onTick(long millisUntilFinished) {   
			tv.setText("请等待30秒(" + millisUntilFinished / 1000 + ")...");   
			Toast.makeText(NewActivity.this, millisUntilFinished / 1000 + "", Toast.LENGTH_LONG).show();//toast有显示时间延迟     
		}  
	}   
}

       主要是重写onTick和onFinsh这两个方法，onFinish()中的代码是计时器结束的时候要做的事情；onTick(Long m)中的代码是你倒计时开始时要做的事情，参数m是直到完成的时间，构造方法MyCount()中的两个参数中，前者是倒计的时间数，后者是倒计每秒中间的间隔时间，都是以毫秒为单位。例如要倒计时30秒，每秒中间间隔时间是1秒，两个参数可以这样写MyCount(30000,1000)。 将后台线程的创建和Handler队列封装成为了一个方便的类调用。

   当你想取消的时候使用mc.cancel()方法就行了。