TreeSet多字段排序

package st;

public class PersonBean implements Comparable<Object>{

    private String name;
    private int age;    

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

    public String getName() {
        return name;
    }    

    public int getAge() {
        return age;
    }    

    @Override
    public int compareTo(Object obj) {
        if (!(obj instanceof PersonBean))
            throw new RuntimeException();
        /**
         * 在这里定义比较对象大小的方法
         * 先进行年龄的比较，年龄不相等再进行姓名的比较
         * 如果年龄与姓名都相等，那么就代表同一个对象
         */
        PersonBean pe = (PersonBean) obj;
        if (this.age > pe.age)
            return ;
        if (this.age == pe.age) {
            return this.name.compareTo(pe.name);
        }    

        return -;
    }    

}

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

public class Dup {
        public static void main(String[] args) {    

            // 向这个集合中存储自定义对象
            TreeSet<PersonBean> ts = new TreeSet<PersonBean>();
            ts.add(new PersonBean("lishi", ));
            ts.add(new PersonBean("lishi1", ));
            ts.add(new PersonBean("lishi56", ));
            ts.add(new PersonBean("lishi4", ));    

            //获取迭代器，取出其中的元素
            Iterator<PersonBean> it = ts.iterator();
            while (it.hasNext()) {
                PersonBean pe = (PersonBean) it.next();
                System.out.println(pe.getAge() + "  " + pe.getName());
            }    

}
}