Java多线程实现自然同步（内含演示案例）

public class Producer extends Thread{
    
    private String name;
    private Market mkt;
    static int count;
    
    public Producer(String name, Market mkt) {
        super(name);
        this.mkt = mkt;
    }
    
    @Override
    public void run() {
        this.name = Thread.currentThread().getName();
        System.out.println(name+"开始生产了！");
        for (int i = 0; i < 5; i++) {
            try {
                Thread.sleep((long)(2000*Math.random()));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            count ++;
            String goods = "商品"+count;
            mkt.set(goods);
        }
        System.out.println(name+"生产完成！");
    }
}

public class Consumer extends Thread{
    
    private String name;
    private Market mkt;
    
    public Consumer(String name,Market mkt){
        super(name);
        this.mkt = mkt;
    }
    
    @Override
    public void run() {
        this.name = Thread.currentThread().getName();
        System.out.println(name+"开始消费了！");
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 10; i++) {
            try {
                Thread.sleep((long)(2000*Math.random()));
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            String shoppingCart = mkt.get();
            sb.append(shoppingCart).append(" | ");
        }
        System.out.println(name+"消费者购物完毕，所购清单如下：");
        System.out.println("\t"+sb);
    }
}

public class Market {
    
    private String shelf;
    private boolean flag;
    
    public synchronized void set(String goods){
        String name = Thread.currentThread().getName();
        while(flag){
            try {
                System.out.println(name+"试图上货但货架已满，请等待消费！");
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        this.shelf = goods;
        this.flag = true;
        System.out.println(name+"已将"+goods+"上货，可以消费了！");
        this.notify();
    }
    
    public synchronized String get(){
        String name = Thread.currentThread().getName();
        while(!flag){
            System.out.println(name+"试图购物，但货架已空，请等待上货！");
            try {
                this.wait();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        String shoppingCart = shelf;
        this.shelf = null;
        this.flag = false;
        System.out.println(name+"购买了一个"+shoppingCart+"！");
        this.notify();
        return shoppingCart;
    }
}

public class Start {
    public static void main(String[] args) {
        Market mkt = new Market();
        Producer p1 = new Producer("工人1", mkt);
        Producer p2 = new Producer("工人2", mkt);
        Consumer c = new Consumer("顾客", mkt);
        p2.start();
        c.start();
        p1.start();
    }
}