Java多线程编程之访问共享对象和数据的方法

package com.ljq.test.thread;
 
/**
 * 多个线程之间共享数据的方式
 *
 * 设计四个线程，其中两个线程每次对j增加1，另外两个线程每次对j减少1。循环100次。
 *
 * @author Administrator
 *
 */
public class MultiThreadShareData {
  private static ShareData data1 = new ShareData();
 
  public static void main(String[] args) {
    ShareData data2 = new ShareData();
    new Thread(new DecrementRunnable(data2)).start();
    new Thread(new IncrementRunnable(data2)).start();
 
    final ShareData data1 = new ShareData();
    new Thread(new Runnable() {
      @Override
      public void run() {
        data1.decrement();
 
      }
    }).start();
    new Thread(new Runnable() {
      @Override
      public void run() {
        data1.increment();
 
      }
    }).start();
 
  }
 
}
 
/**
 * 创建线程类，负责对j减少1
 *
 * @author Administrator
 *
 */
class DecrementRunnable implements Runnable {
  private ShareData data;
 
  public DecrementRunnable(ShareData data) {
    this.data = data;
  }
 
  public void run() {
    for(int i=0; i<100; i++){
      data.decrement();
    }
     
  }
}
 
/**
 * 创建线程类，负责对j增加1
 *
 * @author Administrator
 *
 */
class IncrementRunnable implements Runnable {
  private ShareData data;
 
  public IncrementRunnable(ShareData data) {
    this.data = data;
  }
 
  public void run() {
    for(int i=0; i<100; i++){
      data.increment();
    }
     
  }
}
 
/**
 * 封装共享数据
 *
 * @author Administrator
 *
 */
class ShareData {
  private int j = 0;
 
  /**
   * 每次对j增加1
   */
  public synchronized void increment() {
    j++;
    System.out.println("j++="+j);
  }
 
  /**
   * 每次对j减少1
   */
  public synchronized void decrement() {
    j--;
    System.out.println("j--="+j);
  }
   
   
}