public class Task extends Thread{public void run() {int size = 64;while(size >=4){write(size);delete();size /= 2;}}private void write(int size){//省略具体的写数据方法，判断是否写满
    }private void delete(){//省略删除的方法
    }
}

import java.util.HashMap;
import java.util.Map;/*** 状态信息类*/
public class Status {private int finishCount = 0;private int threadCount = 0;// 存储每个线程的状态private Map<Integer, Boolean> maps;public Status(int threadCount) {this.maps = new HashMap<Integer, Boolean>();this.threadCount = threadCount;}//更新当前线程是否在等待状态，status = true表示已经在等待了public synchronized void setStatus(int threadIndex, boolean statu) {maps.put(threadIndex, statu);}public boolean getStatus() {boolean result = true;for (Map.Entry<Integer, Boolean> entry : maps.entrySet()) {result = result && entry.getValue();}return result;}// 更新已经完成的线程个数(全部各个阶段执行完调用)public synchronized void updateFinishCount() {this.finishCount += 1;}public int getFinishCount() {return finishCount;}
}

/*** 观察线程*/
public class Watcher extends Thread{private int threadCount = 0;private Status status;public Watcher(Status status,int threadCount ) {this.status = status;this.threadCount = threadCount;}public void run() {while(true){//检查是否所有status对象上的线程是否都在等待if(status.getStatus()){status.notifyAll();}//检查是否所有线程全部执行完成if(status.getFinishCount() == threadCount){break;}}}
}

/*** 具体执行任务的线程*/
public class Task extends Thread{private Status status;private int index;public Task(Status status,int index) {this.status = status;this.index =index;}public void run() {int size = 64;while(size >=4){write(size);synchronized (status) {status.setStatus(index, true);//设置为等待状态try {status.wait();} catch (InterruptedException e) {e.printStackTrace();}}status.setStatus(index, false);//取消等待状态
            delete();synchronized (status) {status.setStatus(index, true);//设置为等待状态try {status.wait();} catch (InterruptedException e) {e.printStackTrace();}}status.setStatus(index, false);//取消等待状态size /= 2;}}private void write(int size){//省略具体的写数据方法，判断是否写满
    }private void delete(){//省略删除的方法
    }
}

*** 具体执行任务的线程*/
public class Task extends Thread {private CyclicBarrier cyclicBarrier;public Task(CyclicBarrier cyclicBarrier) {this.cyclicBarrier = cyclicBarrier;}public void run() {int size = 64;while (size >= 4) {write(size);try {cyclicBarrier.await();} catch (InterruptedException e) {e.printStackTrace();} catch (BrokenBarrierException e) {//捕获到该异常的话，表示这个线程不用等待了，需要处理一下，唤醒其他阻塞的线程
                e.printStackTrace();}delete();try {cyclicBarrier.await();} catch (InterruptedException e) {e.printStackTrace();} catch (BrokenBarrierException e) {e.printStackTrace();}size /= 2;}}private void write(int size) {// 省略具体的写数据方法，判断是否写满
    }private void delete() {// 省略删除的方法
    }
}

public class Test {private static final int THREAD_COUNT = 4;public static void main(String[] args) {CyclicBarrier barrier = new CyclicBarrier(THREAD_COUNT);for(int i=0;i<THREAD_COUNT;i++){new Task(barrier).start();}}
}