java多线程通信 例子

 package com.cl.www.thread;

 public class NumberHolder {

     private Integer number = 0;

     // 增加number
     public synchronized void increaseNum(){
         //不是0就不加
         while(number != 0){
             try {
                 this.wait();
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
         }
         number++;
         System.out.println("number的值为："+number);
         this.notifyAll(); //通知其它线程
     }

     //减少number
     public synchronized void decreaseNum(){
         //如果等于0就不减少
         while(number == 0){
             try {
                 this.wait();
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
         }
         number--;
         System.out.println("number的值为："+number);
         this.notifyAll(); //通知其它线程
     }
 }

 package com.cl.www.thread;
 /**
  *
  * 增加number
  */
 public class IncreaseThread implements Runnable{

     private NumberHolder numberHolder;

     public IncreaseThread(NumberHolder numberHolder) {
         this.numberHolder = numberHolder;
     }

     @Override
     public void run() {
         int i = 0;
         while(i<10){
             try {
                 Thread.sleep(1000);
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
             numberHolder.increaseNum();
             i++;
         }
     }
 }

 package com.cl.www.thread;

 /**
  * 减少number
  *
  */
 public class DecreaseThread implements Runnable{

     private NumberHolder numberHolder;

     public DecreaseThread(NumberHolder numberHolder) {

         this.numberHolder = numberHolder;
     }
     @Override
     public void run() {
         int i =0;
         while(i<10){
             try {
                 Thread.sleep((long)Math.random()*1000);
             } catch (InterruptedException e) {
                 e.printStackTrace();
             }
             numberHolder.decreaseNum();
             i++;
         }
     }
 }

 package com.cl.www.thread;

 public class MainTest {
     public static void main(String[] args) {

         NumberHolder numberHolder = new NumberHolder();

         IncreaseThread increaseThread = new IncreaseThread(numberHolder);
         DecreaseThread decreaseThread = new DecreaseThread(numberHolder);

         Thread th1 = new Thread(increaseThread);   // 加 number
         Thread th2 = new Thread(decreaseThread);   // 减 number

         Thread th3 = new Thread(increaseThread);    // 加 number
         Thread th4 = new Thread(decreaseThread);    // 减 number

         th1.start();
         th2.start();

         th3.start();
         th4.start();
     }
 }

输出结果