public class ViolentAccessDemo {
   public static void main(String[] args) {
      ViolentObject violentObject = new ViolentObject();
      Thread thread1 = new Thread(new ThreadAccess(violentObject));
      Thread thread2 = new Thread(new ThreadAccess(violentObject));
      thread1.start();
      thread2.start();
      for(int i=0;i<10;i++){
         violentObject.print();
         try{
            Thread.sleep(500);            
         }catch(InterruptedException e){}
      }
   }

}

class ViolentObject{
   private int x;
   private int y;
   private int z;
   private int a;
   public void increase(){  //这里输出的值是不一样，因为
            //x++ 在刚被执行完之后，就退出时间片，而下次进来的线程又重新执行x++。
           //那么肯定地说x的值加到最后，必然是最大的。可是事实上，并不是如此。
            //加最一个synchronized是不是保证这句代码被执行完解锁，再退出CPU时间片。
           //很不解。
      x++;
      y++;
      z++;
      a++;
   }
   public void print(){
      System.out.println("x="+x+",y="+y+",z="+z+",a="+a);
   }
}

class ThreadAccess implements Runnable{
   private ViolentObject violentObject;
   public ThreadAccess(ViolentObject violentObject){
      this.violentObject = violentObject;
   }
   public void run(){
      while(true) violentObject.increase();
   }
}

1    ALOAD 0
2    DUP
3    GETFIELD ViolentObject.x : I
4    ICONST_1
5    IADD
6    PUTFIELD ViolentObject.x : I

------解决方案--------------------