TreeSet存储自定义对象，并对对象排序的两种方式

想有一个自定义对象，先搞一个Student类。

//Student.java

package com.huowolf;

public class Student implements Comparable{
private String name;
private int age;

public Student(String name, int age) {
this.name = name;
this.age = age;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}

public int compareTo(Object obj) {
if(!(obj instanceof Student))
throw new RuntimeException("不是学生对象");

Student stu=(Student)obj;
if(this.age>stu.age)
return 1;
if(this.age==stu.age)
return this.name.compareTo(stu.name);
return -1;
}

}

package com.huowolf;

import java.util.Iterator;
import java.util.TreeSet;

/**
* @author huowolf
*排序的第一种方式：让元素自身具备比较性。
*元素需要实现Comparable接口，覆盖compareTo方法
*这种方式也元素的自然顺序
*/
public class TreeSetDemo {

public static void main(String[] args) {
TreeSet<Object> ts= new TreeSet<Object>();
ts.add(new Student("lisi01",22));
ts.add(new Student("lisi02",20));
ts.add(new Student("lisi03",18));
ts.add(new Student("lisi04",25));
ts.add(new Student("lisi05",18));

Iterator it = ts.iterator();
while(it.hasNext())	{
Student stu =	(Student) it.next();
System.out.println("姓名："+stu.getName()+" 年龄："+stu.getAge());
}

}

}

package com.huowolf;

import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;

/**
* @author huowolf
*排序的第二种方式：当元素自身不具备比较性时，让集合自身具备比较性。
*在集合初始化时，指定比较器。
*/
public class TreeSetDemo2 {

public static void main(String[] args) {
TreeSet<Object> ts= new TreeSet<Object>(new MyCompare());
ts.add(new Student("lisi01",22));
ts.add(new Student("lisi02",20));
ts.add(new Student("lisi03",18));
ts.add(new Student("lisi04",25));
ts.add(new Student("lisi02",27));

Iterator it = ts.iterator();
while(it.hasNext())	{
Student stu =	(Student) it.next();
System.out.println("姓名："+stu.getName()+" 年龄："+stu.getAge());
}

}

}

class MyCompare implements Comparator	{
public int compare(Object o1,Object o2)	{
Student s1 = (Student) o1;
Student s2 = (Student) o2;
int num = s1.getName().compareTo(s2.getName());
if(num==0)
//return s1.getAge()-(s2.getAge());
return new Integer(s1.getAge()).compareTo(new Integer(s2.getAge()));
return num;
}
}