写一个多线程控制工人接活和工作的例子（使用synchronized wait notifyAll）

package org.example;

public class StudyWaitAndNotify {
    public static void main(String[] args) {
        WorkManNeedToDo a = new WorkMan();
        Leader l1 = new Leader(a, 25);
        Leader l2 = new Leader(a, 20);

        Tester t1 = new Tester(a, 25);
        Tester t2 = new Tester(a, 20);


        l1.start();
        l2.start();

        t1.start();
        t2.start();

    }
}

class Leader extends Thread {
    private WorkManNeedToDo workManNeedToDo ;
    private int num ;

    public Leader (WorkManNeedToDo a, int num){
        workManNeedToDo=a;
        this.num = num;

    }
    @Override
    public void run() {
        workManNeedToDo.getWork(num);
    }
}

class Tester extends Thread {
    private WorkManNeedToDo workManNeedToDo ;
    private int num ;
    public Tester (WorkManNeedToDo a, int num){
        workManNeedToDo=a;
        this.num = num;

    }
    @Override
    public void run() {
        workManNeedToDo.doWork(num);
    }
}

class WorkMan implements WorkManNeedToDo {
    private Object lock = new Object();
    private int MAXWORKNUM = 35;// 最多45人天
    private int nowWorkNum ;


    @Override
    public void doWork(int num) {
        System.out.println("开始准备工作，当前工作量："+nowWorkNum+"要完成的工作："+num);
        synchronized (lock){
            // nowWorkNum 随时可能边 先锁住
            while (num > nowWorkNum){
                // 要干的活儿得小于现在有的活儿 先锁住
                System.out.println("要干的活儿得小于现在有的活儿 先锁住");
                try {
                    lock.wait();
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
            nowWorkNum = nowWorkNum-num;
            System.out.println("工作后，当前工作量："+nowWorkNum+"已经完成的工作："+num);
            lock.notifyAll();
        }
    }

    @Override
    public void getWork(int num) {
        System.out.println("开始准备接活儿，当前工作量："+nowWorkNum+"要接手的工作："+num);
        synchronized (lock){
            // nowWorkNum 随时可能变 先锁住
            while (num+nowWorkNum > MAXWORKNUM){
                // 活儿太多了 没发接 先干完别的再说
                System.out.println("活儿太多了 没发接 先干完别的再说");
                try {
                    lock.wait();
                }catch (Exception e){
                    e.printStackTrace();
                }
            }
            nowWorkNum = nowWorkNum+num;
            System.out.println("接活后，当前工作量："+nowWorkNum+"已经接手的工作："+num);
            lock.notifyAll();
        }
    }
}
interface WorkManNeedToDo {
    void doWork(int num);// 工作 减少工作量
    void getWork(int num);// 接受任务 增加工作量
}

参考帖子https://www.cnblogs.com/moongeek/p/7631447.html