java多线程实验03

实验volatile的作用

 

如果结果保持不变才起到了同步的作用，否则就存在线程安全问题.

 

package org.coffeesweet.test01;

public class Test03 {
	private volatile  int a=20;
	public static void main(String...args) throws InterruptedException{
		Test03 t03=new Test03();
		Thread ta=t03.new A("a");
		Thread tb=t03.new B("b");
//		new Thread(t03.new A(),"a");
		System.out.println("a---start:"+t03.a);
		ta.start();
		tb.start();
		ta.join();
		tb.join();
		System.out.println("a---end:"+t03.a);
	}
	
	private class A extends Thread{
		public A(){
			super();
		}
		public A(String name){
			super(name);
		}
		public void addA(){
			for(int i=0;i<100000;i++)
			a=a+1;
		}
		@Override
		public void run() {
			System.out.println("execute:A:start:"+a);
			addA();
			System.out.println("execute:A:end:"+a);
		}
	}
	private class B extends Thread{
		public B(){
			super();
		}
		public B(String name){
			super(name);
		}
		public void minusA(){
			for(int i=0;i<100000;i++)
			a=a-1;
		}
		@Override
		public void run() {
			System.out.println("execute:B:start:"+a);
			minusA();
			System.out.println("execute:B:end:"+a);
		}
	}
}