三个 线程不安全的案例

三个 线程不安全的案例

案例1 :

package Thread;

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<String>();
        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());
    }

}

案例二：

package Thread;

//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 grilFriend=new Drawing(account,100,"grilFriend");

        you.start();
        grilFriend.start();

    }
}


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

    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;
    //现在手里多少钱
    int nowMoney;

    public Drawing(Account account,int drawingMoney,String name){
    
    
        super(name);
        this.account=account;
        this.drawingMoney=drawingMoney;
        this.nowMoney=nowMoney;
    }

    //取钱
    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) {
    
    
            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);
    }

}

案例三：

package Thread;

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

        new Thread(bt,"旅客").start();
        new Thread(bt,"黄牛党").start();
        new Thread(bt,"我自己").start();
    }

}

class BuyTicket implements Runnable{
    
    

    //票
    private int piao=10;
    boolean flag=true;
    //买票
    @Override
    public void run() {
    
    
        while (flag){
    
    
            buy();
        }
    }

    //买票的方法
    public void buy(){
    
    
        if (piao<=0){
    
    
            flag=false;
            return;
        }
        try {
    
    
            Thread.sleep(100);
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        }
        System.out.println(Thread.currentThread().getName()+"买到了第"+piao--+"票");
    }
}