How to implement inter-thread communication in Java?

What is thread communication and how to implement it?

The so-called thread communication is to send data to each other between threads. Thread communication is usually achieved by sharing a data.

Threads will decide what to do based on the shared data, and notify other threads what to do.

Common models of thread communication

Producer and consumer models: The producer thread is responsible for producing data, and the consumer thread is responsible for consuming data.

Requirements: After the producer thread has finished producing the data, it wakes up the consumer and then waits for itself; after the consumer has finished consuming the data, it wakes up the producer and then waits for itself

public class 多线程_5线程通信 extends Thread{
 
    public static void main(String[] args) {
        //定义线程类，创建一个共享的账户对象
        account3 a=new account3("abc",0);
        //创建两个取钱的线程对象
        new drawthread3(a,"小明").start();
        new drawthread3(a,"小红").start();
        //创建三个存钱的线程对象
        new savethread(a,"存钱罐1号").start();
        new savethread(a,"存钱罐2号").start();
        new savethread(a,"存钱罐3号").start();
    }
}
//存钱的线程类
class savethread extends Thread{
    //接收处理的账户对象
    private account3 acc;
    public savethread(account3 acc,String name){
        super(name);
        this.acc=acc;
    }
    public void run(){
        try {
            while (true){
                //存钱
                acc.savemoney(100000);
                //休眠2秒
                Thread.sleep(2000);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
//取钱的线程类
class drawthread3 extends Thread{
    //接收处理的账户对象
    private account3 acc;
    public drawthread3(account3 acc,String name){
        super(name);
        this.acc=acc;
    }
    public void run(){
        try {
            while (true){
                //取钱
                acc.drawmoney3(100000);
                //休眠2秒
                Thread.sleep(2000);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
class account3{
    private String cartId;
    private double money;//账户余额
 
    public account3() {
    }
 
    public account3(String cartId, double money) {
        this.cartId = cartId;
        this.money = money;
    }
 
    public String getCartId() {
        return cartId;
    }
 
    public void setCartId(String cartId) {
        this.cartId = cartId;
    }
 
    public double getMoney() {
        return money;
    }
 
    public void setMoney(double money) {
        this.money = money;
    }
 
    public synchronized void savemoney(double money) {
        //先获取是谁来存钱，线程名即是人名
        String name=Thread.currentThread().getName();
        //判断账户是否有钱
        try {
            if(this.money==0){
                //没钱，存钱
                this.money+=money;
                System.out.println(name+"来存钱，存了："+money+"存钱后余额为："+this.money);
                //有钱了
                //唤醒所有线程
                this.notifyAll();
                //锁对象，让当前线程进入等待
                this.wait();
            }else {
                //有钱,不存钱
                //唤醒所有线程
                this.notifyAll();
                //锁对象，让当前线程进入等待
                this.wait();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    public synchronized void drawmoney3(double money) {
        //先获取是谁来取钱，线程名即是人名
        String name=Thread.currentThread().getName();
        try {
            //判断账户是否够钱
            if(this.money>=money){
                //有钱，取钱
                this.money-=money;
                System.out.println(name+"来取钱成功,取了："+money+"余额是："+this.money);
                //没钱了
                //唤醒所有线程
                this.notifyAll();
                //锁对象，让当前线程进入等待
                this.wait();
            }else{
                //余额不足
                //唤醒所有线程
                this.notifyAll();
                //锁对象，让当前线程进入等待
                this.wait();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

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