三大不安全案例

不安全的取钱 UnsafeBank

package com.guo.syn;

//不安全的取钱
public class UnsafeBank {
    public static void main(String[] args) {
        //账户
        Account account = new Account(100,"结婚基金");

        Drawing chenguo = new Drawing(account,50,"陈果");
        Drawing liyue = new Drawing(account,100,"李悦");

        chenguo.start();
        liyue.start();

    }
}

//账户
class Account {
    int money;
    String name;

    public Account(int money,String name) {
        this.name = name;
        this.money = money;
    }
}

//银行
class Drawing extends Thread{
    Account account;//账户
    //取了多少钱
     int drawingMoney;
    //现在手里有多少钱
    int nowMoney;


    public Drawing(Account account,int drawingMoney,String name){

        super(name);
        this.account = account;
        this.drawingMoney = drawingMoney;

    }
//取钱
    @Override
    public void run() {
        //判断有没有钱
        if (account.money-drawingMoney<0){
            System.out.println(Thread.currentThread().getName()+"钱不够，取不了");
            return;
        }

        //sleep 可以放大问题的发生性
        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }

        //卡内余额 = 余额 - 取走的钱
        account.money = account.money-drawingMoney;
        //手里的钱
        nowMoney = nowMoney+drawingMoney;

        System.out.println(account.name+"余额为："+account.money);

        System.out.println(this.getName()+"手里的钱："+nowMoney);

    }
}

不安全买票 UnsafeBuyTicket

package com.guo.syn;

//不安全买票
//线程不安全，有负数
public class UnsafeBuyTicket {
    public static void main(String[] args) {
        BuyTicket station = new BuyTicket();

        new Thread(station,"帅气的陈果").start();
        new Thread(station,"美丽的李悦").start();
        new Thread(station,"操蛋的黄牛").start();
    }
}


class BuyTicket implements Runnable{

    //票
    private int ticketNums = 10;
    boolean flag = true; //外部停止方式
    @Override
    public void run() {
        //买票
        while (flag){
            buy();
        }

    }

    private void buy(){

        if (ticketNums<=0){
            flag = false;
            return;
        }

        //模拟延时
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }

        //买票
        System.out.println(Thread.currentThread().getName()+"-->买到了第"+ticketNums--+"张票");
    }



}

UnsafeList

package com.guo.syn;

import java.sql.Array;
import java.util.ArrayList;

public class UnsafeList {
    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<>();
        for (int i = 0; i < 10000; i++) {
            new Thread(()->{
                list.add(Thread.currentThread().getName());
            }).start();
        }

        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }

        System.out.println(list.size());

    }
}