多线程不安全的案例以及同步方法及同步块

买票

//不安全的买票
public class UnsafeBuyTicket {
    public static void main(String[] args) {
        BuyTicket station = new BuyTicket();
        new Thread(station,"我").start();
        new Thread(station,"你").start();
        new Thread(station,"黄牛").start();
    }
}

class BuyTicket implements Runnable{
    //票
    private int ticketNums = 10;
    boolean flag = true;

    @Override
    public void run() {
        while(flag){
            buy();
        }
    }

    private synchronized 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()+ticketNums--+"张票");
    }
}

银行取钱

public class UnsafeBank {
    public static void main(String[] args) {
        Count cout = new Count(100,"基金");
        moneychang moneychang = new moneychang(cout,90,"girl");
        moneychang moneychang1 = new moneychang(cout,50,"boy");

        moneychang.start();
        moneychang1.start();
    }
}
class Count{
    String name;
    int money;
    public Count(int money,String name){
        this.money = money;
        this.name = name;
    }
}
class moneychang extends Thread {
    Count count;
    int takemoney;
    int handmon;

    @Override
    public void run() {
       synchronized{
            if (count.money>takemoney){
            count.money = count.money-takemoney;
            handmon = handmon+takemoney;
            System.out.println(Thread.currentThread().getName()+"取了"+takemoney);
            System.out.println("账户余额"+count.money);
            }else{
                System.out.println("余额不足");
            }
            try {
                Thread.sleep(200);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
      }

    public moneychang(Count count,int takemoney,String name){
        super(name);
        this.count = count;
        this.takemoney = takemoney;
        ;
    }
}

synchronized方法锁的对象是this

synchronized锁的对象是变化的量，需要增删改