1.问题描述：

　　某个类有2个方法func1(),func2(),有threadCount个线程，要求所有线程执行完func1(),再执行func2()。

2.分析：

　　1）所有线程的func1()执行完的标准是什么？

　　2）线程之间怎样共享变量？

3.代码实现

　　1）源代码：

/**
 *
 */
package com.sunny.www.interview;

import java.util.concurrent.atomic.AtomicInteger;

/**
 * 所有线程执行完方法1，再执行方法2
 * @author sunny
 *
 */
public class Syn2Threads implements Runnable {
    private AtomicInteger threadCount;        

    public Syn2Threads(AtomicInteger threadCount) {
        super();
        this.threadCount = threadCount;
    }
    public AtomicInteger getThreadCount() {
        return threadCount;
    }
    public void setThreadCount(AtomicInteger threadCount) {
        this.threadCount = threadCount;
    }
    private void func1(){
        System.out.println(Thread.currentThread().getName() + " execute func1,threadCount=" + threadCount.decrementAndGet());

    }
    private void func2(){
        System.out.println(Thread.currentThread().getName() + " execute func2,threadCount=" + threadCount);
    }

    @Override
    public void run() {
        func1();
        synchronized(threadCount){
            while (0 < threadCount.get())  {
                try {
                    System.out.println(Thread.currentThread().getName() + " func1 not finished totally,threadCount=" + threadCount);
                    threadCount.wait();
                } catch (InterruptedException e) {
                    System.out.println(Thread.currentThread().getName() + " wait error");
                }
            }
            threadCount.notifyAll();
        }
        func2();
    }

    public static void main(String[] args) {
        int threadCount = 5;
        Syn2Threads syn2Threads = new Syn2Threads(new AtomicInteger(threadCount));
        for(int i = 1; i <= threadCount; i++){
            new Thread(syn2Threads,"thread-" + i).start();
        }
    }

}

　　2）运行效果：

thread-2 execute func1,threadCount=4
thread-2 func1 not finished totally,threadCount=3
thread-1 execute func1,threadCount=3
thread-4 execute func1,threadCount=2
thread-4 func1 not finished totally,threadCount=2
thread-1 func1 not finished totally,threadCount=2
thread-5 execute func1,threadCount=1
thread-5 func1 not finished totally,threadCount=1
thread-3 execute func1,threadCount=0
thread-3 execute func2,threadCount=0
thread-5 execute func2,threadCount=0
thread-1 execute func2,threadCount=0
thread-4 execute func2,threadCount=0
thread-2 execute func2,threadCount=0