while循环为什么跳出了还会再运行一次 新人求知道

Question

实体类
package com.pij.bean;

public class bean {
private int num = 501;

public int getNum() {
    return num;
}

public void setNum(int Num) {
    this.num = num - Num;
}

}

实现接口
package com.pij.imp;

import com.pij.bean.bean;

public class imp implements Runnable {
bean bn = new bean();

@Override
public void run() {

    bea(50);

}

public synchronized void bea(int num) {

    while (true) {

        if (bn.getNum() >= num) {

            System.out.println("你在使用网络系统调用的货物预定");
            System.out.println("现存备货：" + bn.getNum());
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
            System.err.println(Thread.currentThread().getName()
                    + "货物调用预定成功");
            bn.setNum(num);
        } else {
            System.out.println("仓库备货不足");
            System.out.println("现存货数量：" + bn.getNum());
            break;

        }


    }
}

}

测试类
package com.pij.text;

import com.pij.imp.imp;

public class test {
public static void main(String[] args) {
imp a = new imp();
Thread b1 = new Thread(a);
Thread b2 = new Thread(a);

    b1.setName("五厂XX");
    b2.setName("二厂XXX\t\t\t\t");
    b1.start();
    b2.start();


}

}

Answer 1

何以见得多运行了一次？你有两个线程，考虑到这个了么