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);  }      }