Java多线程-线程3大不安全案例

package com.wyh.thread;
/**
 * @program: Thread
 * @description: 线程不安全的案例 买票
 * @author: 魏一鹤
 * @createDate: 2022-01-09 21:55
 **/
//不安全的买票
//线程不安全 有负数 有重复
public class TestThreadUnSafeBuyTicket {
    //主线程 用户线程
    public static void main(String[] args){
        //买票线程对象
        BuyTicket buyTicket = new BuyTicket();
        //多个线程来买票
       new Thread(buyTicket,"张三").start();
       new Thread(buyTicket,"小明").start();
       new Thread(buyTicket,"黄牛党").start();
    }
}
//多线程去买票
class BuyTicket implements  Runnable {
    //票
    int tickNum=10;
    //外部停止方式
    // 是否停止标识 true不停止 false停止
    boolean flag=true;
    @Override
    public void run() {
        //买票
        while (flag) {
            try {
                buy();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    //买票方法
    private  void buy() throws InterruptedException {
        //判断是否有票 没有票直接return不做处理
        if(tickNum<=0){
            //标识符为false 线程停止
            flag=false;
            return;
        }
        //模拟延时 放大问题
        Thread.sleep(100);
        //有票的话就直接自减
        System.out.println(Thread.currentThread().getName() + "买到了第"+tickNum--+"张票");
    }
}

package com.wyh.thread;
/**
 * @program: Thread
 * @description: 线程不安全例子 银行取钱
 * @author: 魏一鹤
 * @createDate: 2022-01-09 22:19
 **/
//不安全的取钱 两个人去银行取钱
public class TestThreadUnSafeBank  {
    public static void main(String[] args){
        //账户
        Account account = new Account(100,"结婚基金");
        //我要取钱50
        Drawing you=new Drawing(account,50,"你");
        //女朋友取100
        Drawing girlFriend=new Drawing(account,100,"girlFriend");
        //多线程取钱
        you.start();
        girlFriend.start();
    }
}
//账户
class Account{
    //余额
    int money;
    //卡号
    String name;
    //有参构造方法
    public Account(int money, String name) {
        this.money = money;
        this.name = name;
    }
}
//银行 模拟取款
class Drawing  extends Thread{
    //账户
    Account account;
    //取了多少钱
    int drawingMoney;
    //现在手里有多少钱
    int nowMoney;
    //有参构造方法
   public Drawing(Account account,int drawingMoney,String name){
       super(name);
       this.account=account;
       this.drawingMoney=drawingMoney;
   }
   //重写run方法
    //取钱
    @Override
    public void run() {
       //判断有没有钱
        if(account.money-drawingMoney<0){
            System.out.println(Thread.currentThread().getName() + "钱不够了,取不了");
            return;
        }
        //模拟延时 放大问题
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        //银行卡内余额=余额-你取得钱
        account.money=account.money-drawingMoney;
        //你手里的钱
        nowMoney=nowMoney+drawingMoney;
        //打印账户余额
        System.out.println(account.name +"的余额为:"+account.money);
        //打印你手里的钱  this.getName()=Thread.currentThread().getName()  也是当前线程的名称
        System.out.println(this.getName()+"手里的钱:"+nowMoney);
    }
}

package com.wyh.thread;
import java.util.ArrayList;
import java.util.List;
import java.util.Vector;
/**
 * @program: Thread
 * @description: 线程不安全list(arrayList)
 * @author: 魏一鹤
 * @createDate: 2022-01-09 22:50
 **/
//线程不安全的集合 ArrayList线程就是不安全的 与之对应的list实现Vector是线程安全的
public class TestThreadUnSafeList {
   public static void main(String[] args) throws InterruptedException {
       List<String> arrayList = new ArrayList<String>();
       //使用线程循环插入元素
       for (int i = 0; i < 10000; i++) {
           //10000个线程
           new Thread(()->{
               //把线程的名字添加到list中
               arrayList.add(Thread.currentThread().getName());
           });
       }
       Thread.sleep(3000);
       //list的大小
       System.out.println(arrayList.size());
       //ArrayList线程不安全的原因是什么呢
       //多个线程操作同一个位置,把两个数组添加到同一位置,就会把元素进行覆盖,进行数据丢失 
   }
}