为什么打出来 是这样的
student@17590db
student@17943a4
student@480457
import java.util.*;
class test2
{
public static void pp(Collection c)
{
Iterator i=c.iterator();
while(i.hasNext())
{
System.out.println(i.next());
}
}
public static void main(String[] args)
{
student s1=new student(1,"wanghai");
student s2=new student(3,"lihai");
student s3=new student(2,"jianghai");
ArrayList a1=new ArrayList();
a1.add(s1);
a1.add(s2);
a1.add(s3);
Collections.sort(a1);
pp(a1);
}
}
class student implements Comparable
{
int num;
String name;
student(int num,String name)
{
this.num=num;
this.name=name;
}
public int compareTo(Object o)
{
student s=(student)o;
return num>s.num ? 1 : (num==s.num ? 0 : -1);
}
public String ToString()
{
return num+":"+name;
}
}

自己重定义一个toString方法就OK了

public String ToString()
{
return num+":"+name;
}

你定义的方法名写错了 没有重写toString方法
应该为toString

public class TextTest
{
int len=10000;// 求值范围
int l,m,n;
public TextTest()
{

}

public static void main(String args[])throws Exception
{
//TextTest tt = new TextTest();
Employee e1=new Employee("zhaobo",21);
Employee e2=new Employee("zhaoyunxia",20);
Employee e3=new Employee("baby",2);

FileOutputStream raf =new FileOutputStream("employee.txt");
ObjectOutputStream oos = new ObjectOutputStream(raf);
oos.writeObject(e1);
oos.writeObject(e2);
oos.writeObject(e3);
oos.flush();
raf.close();
oos.close();

FileInputStream raf2 =new FileInputStream("employee.txt");
ObjectInputStream ois = new ObjectInputStream(raf2);
Employee temp_oob = (Employee)ois.readObject();;
System.out.println(" "+temp_oob.getName()+" "+temp_oob.getAge());


temp_oob = (Employee)ois.readObject();;
System.out.println(" "+temp_oob.getName()+" "+temp_oob.getAge());

temp_oob = (Employee)ois.readObject();;
System.out.println(" "+temp_oob.getName()+" "+temp_oob.getAge());
raf2.close();
ois.close();
}

}

class Employee implements Serializable
{
private String name;
private int age;
public static final int LEN=14;

public Employee()
{

}
public Employee(String name,int age)
{
if(name.length()>LEN)
{
name=name.substring(0,LEN);
}
else
while(name.length()<LEN)
{
name+="\u0000";
}
this.name=name;
this.age=age;
}

//method: getName(),getAge()
public String getName()
{
return name;
}

public int getAge()
{
return age;
}

}

//你把Employee类序列化后，直接存取对象不是很好吗？

谢谢各位了,能指出我错.!!