这个问题就很离谱..人家运行就成功,我就失败

package gatherandgenericity;

import java.io.*;
import java.util.Date;
public class TestObjectStream {
    public static void main(String[] args) throws IOException, ClassNotFoundException {
        Person p = in();
        Person p2 = out();
        System.out.println(p);
        System.out.println(p2);
    }
    public static Person out() throws IOException {
        ObjectOutputStream oos = new ObjectOutputStream(new
                FileOutputStream("d:/Object.txt",false));
        Person p = new Person("张大",22000,50);
        oos.writeObject(p);
        oos.flush();
        oos.close();
        return p;
    }
    public static Person in() throws IOException, ClassNotFoundException {
        ObjectInputStream ois = new ObjectInputStream(new
                FileInputStream("d:\\Object.txt"));
        Person p = (Person)ois.readObject();
        ois.close();
        System.out.println(p.toString());
        return p;
    }
}

package gatherandgenericity;

import java.io.Serializable;

public class Person implements Serializable  {
    private String name;
    private double sal;
    private int age;
    public Person(){
        super();
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", sal=" + sal +
                ", age=" + age +
                '}';
    }

    public Person(String name, double sal, int age) {
        this.name = name;
        this.sal = sal;
        this.age = age;
    }
}

哪儿有问题?