jdk1.5以后的多线程同步方式

jdk1.5以后有了java.util.concurrent包

里面对同步提供了相当多的支持

例如lock atomic以及一些可同步操作的容器

下面给出一个常见的多线程面试题及其对应实现

有三个线程ID分别是A、B、C,请有多线编程实现，在屏幕上循环打印10次ABCABC

采用AtomicInteger来实现这个，

不多说了，上代码，还是相当简单易懂的

可以对concurrent包见一斑。。

import java.util.concurrent.atomic.AtomicInteger;

public class Print extends Thread{
    //专门为同步用的　用integer不行，每次都会新建的
    private AtomicInteger synObj;
    private int count;
    private String s;
    private int flag;
    private int total = 0;

    public Print(int count,AtomicInteger atomicInteger,String s,int flag) {
        this.count = count;
        this.synObj = atomicInteger;
        this.s = s;
        this.flag = flag;
    }
    public void run() {
        while(true) {
            synchronized(synObj) {
                if(synObj.intValue()%3 == flag) {
                    total++;
                    synObj.set(synObj.intValue()+1);
                    System.out.println(s);
                    synObj.notifyAll();
                    if(total == count) {
                        break;
                    }
                }else {
                    try{
                        synObj.wait();
                    }catch(Exception e){
                        e.printStackTrace();
                    }
                }
            }
        }
    }
    public static void main(String[]args) throws Exception {
        AtomicInteger synObj = new AtomicInteger(0);
        Print a = new Print(10,synObj,"A",0);
        Print b = new Print(10,synObj,"B",1);
        Print c = new Print(10,synObj,"C",2);
        a.start();
        b.start();
        c.start();
    }
}

import java.util.concurrent.atomic.AtomicInteger; public class Print extends Thread{ //专门为同步用的　用integer不行，每次都会新建的 private AtomicInteger synObj; private int count; private String s; private int flag; private int total = 0; public Print(int count,AtomicInteger atomicInteger,String s,int flag) { this.count = count; this.synObj = atomicInteger; this.s = s; this.flag = flag; } public void run() { while(true) { synchronized(synObj) { if(synObj.intValue()%3 == flag) { total++; synObj.set(synObj.intValue()+1); System.out.println(s); synObj.notifyAll(); if(total == count) { break; } }else { try{ synObj.wait(); }catch(Exception e){ e.printStackTrace(); } } } } } public static void main(String[]args) throws Exception { AtomicInteger synObj = new AtomicInteger(0); Print a = new Print(10,synObj,"A",0); Print b = new Print(10,synObj,"B",1); Print c = new Print(10,synObj,"C",2); a.start(); b.start(); c.start(); } }