三大不安全案例

package com.wang.multiThread.syn;

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

        new Thread(station,"苦逼的我").start();
        new Thread(station,"牛逼的你们").start();
        new Thread(station,"可恶的黄牛党").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){
            try {
                buy();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    public void buy(){
        //判断是否有票
        if (ticketNums<=0){
            flag = false;
            return;
        }
        //模拟延时
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        //买票
        System.out.println(Thread.currentThread().getName() + "拿到" + ticketNums--);
    }
}
package com.wang.multiThread.syn;

//不安全的取钱
//两个人去银行取钱,账户
public class UnsafeBank {
    public static void main(String[] args) {
        //账户
        Account account = new Account(100, "结婚基金");

        Drawing you = new Drawing(account, 50, "你");
        Drawing girlFriend = new Drawing(account, 100, "girlFriend");

        you.start();
        girlFriend.start();
    }
}

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

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

//银行:模拟取款
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;
        }

        try {
            Thread.sleep(1000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        //卡内余额 = 余额 - 你取的钱
        account.money = account.money - drawingMoney;

        //你手里的钱
        nowMoney = nowMoney - drawingMoney;

        System.out.println(account.name + "余额为:" + account.money);
        //Thread.currentThread().getName() = this.getName()
        System.out.println(this.getName() + "手里的钱" + nowMoney);
    }
}
package com.wang.multiThread.syn;

import java.util.ArrayList;
import java.util.List;

//线程不安全的集合
public class UnsafeList {
    public static void main(String[] args) {
        List<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) {
            e.printStackTrace();
        }
        System.out.println(list.size());
    }
}
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