java 线程之对象的同步和异步(实例讲解)

一、多线程环境下的同步与异步

同步：A线程要请求某个资源，但是此资源正在被B线程使用中，因为同步机制存在，A线程请求不到，怎么办，A线程只能等待下去。

package com.jalja.org.thread.demo01;public class Thread02 { public synchronized void method1(){  System.out.println("method1:"+Thread.currentThread().getName());  try {   Thread.sleep(3000);  } catch (InterruptedException e) {   e.printStackTrace();  } } public synchronized void method2(){  System.out.println("method2:"+Thread.currentThread().getName()); } public static void main(String[] args) {  final Thread02 th=new Thread02();  Thread thread1=new Thread(new Runnable() {   public void run() {    th.method1();   }  },"th2");    Thread thread2=new Thread(new Runnable() {   public void run() {    th.method2();   }  },"th3");    thread1.start();  thread2.start(); }}