三大线程不安全案例

1.不安全买票

package syn;
//不安全买票
public class UnsafeBuyTicket {
    public static void main(String[] args) {
​
        BuyTicket buyTicket=new BuyTicket();
        new Thread(buyTicket,"小明").start();
        new Thread(buyTicket,"小红").start();
        new Thread(buyTicket,"黄牛党").start();
    }
}
​
class BuyTicket implements Runnable{
    private int ticketNums =10;
    boolean flag=true;
    @Override
    public void run() {
        //买票
        while (flag){
            try {
                buy();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
    private  void buy() throws InterruptedException{
        //判断是否有票
        if(ticketNums<=0){
            return;
        }
        //买票
         Thread.sleep(1000);
       
        System.out.println(Thread.currentThread().getName()+"拿到"+ticketNums--);
    }
}
​

2.不安全取钱

package syn;
//不安全取钱
//两个人去银行取钱，账户
public class UnsafeBank {
    public static void main(String[] args) {
    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;//卡明
​
    public Account(int money, String name) {
        this.money = money;
        this.name = name;
    }
}
​
//银行
class Drawing extends Thread{
    Account account;//账户
    int drawingMoney;//取多少钱
    int nowMoney;//还剩多少钱
​
    public Drawing(Account account,int drawingMoney,String name){
        super(name);
        this.account=account;
        this.drawingMoney=drawingMoney;
    }
​
    //取钱的方法
    @Override
    public void run() {
        //判断是否还有钱
        if (account.money-drawingMoney<0){
            System.out.println(Thread.currentThread().getName()+"钱不够，钱取不了");
            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);
        System.out.println(this.getName()+"手里的钱"+nowMoney);
    }
}
​
​

3.线程不安全的集合

package 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) throws InterruptedException {
        List<String> list = new ArrayList<String>();
        for (int i = 0; i < 10000; i++) {
            new Thread(()->{
                list.add(Thread.currentThread().getName());
            }).start();
        }
        Thread.sleep(1000);
        System.out.println(list.size());
    }
}
​