请修改以下代码：package ch15.sort; import java.util.*; class Student implements Comparable{ int height=0; int weight; String name; Student(String n,int h,int w) { name=n; height = h; weight = w; } public int compareTo(Student st) { //两个Student对象大小关系 return (this.height-st.height); } } public class Example15_4_1 { public static void main(String args[ ]) { List list = new LinkedList(); list.add(new Student("张三",188,86)); list.add(new Student("李四",178,83)); list.add(new Student("赵大龙",198,84)); list.add(new Student("李云龙",175,80)); Iterator iter=list.iterator(); System.out.println("排序前,链表中的数据:"); while(iter.hasNext()){ Student stu=iter.next(); System.out.println(stu.name+ "身高:"+stu.height+"体重:"+stu.weight); } Collections.sort(list); System.out.println("排序后,链表中的数据:"); iter=list.iterator(); while(iter.hasNext()){ Student stu=iter.next(); System.out.println(stu.name+ "身高:"+stu.height+"体重:"+stu.weight); } } }具体要求如下：（1）两个学生比较大小结果与他们名字字符串的比较结果一致（2）有时需要按身高来排，若身高相同则按体重排序

修改后的代码如下：

package ch15.sort;

import java.util.*;

class Student implements Comparable<Student> {
    int height = 0;
    int weight;
    String name;

    Student(String n, int h, int w) {
        name = n;
        height = h;
        weight = w;
    }

    public int compareTo(Student st) {
        // 先比较身高
        int cmp = this.height - st.height;
        if (cmp == 0) {
            // 如果身高相同，则比较体重
            cmp = this.weight - st.weight;
        }
        // 如果身高和体重都相同，则按名字字符串比较
        if (cmp == 0) {
            cmp = this.name.compareTo(st.name);
        }
        return cmp;
    }
}

public class Example15_4_1 {
    public static void main(String args[]) {
        List<Student> list = new LinkedList<Student>();
        list.add(new Student("张三", 188, 86));
        list.add(new Student("李四", 178, 83));
        list.add(new Student("赵大龙", 198, 84));
        list.add(new Student("李云龙", 175, 80));
        Iterator<Student> iter = list.iterator();
        System.out.println("排序前,链表中的数据:");
        while (iter.hasNext()) {
            Student stu = iter.next();
            System.out.println(stu.name + "身高:" + stu.height + "体重:" + stu.weight);
        }
        Collections.sort(list);
        System.out.println("排序后,链表中的数据:");
        iter = list.iterator();
        while (iter.hasNext()) {
            Student stu = iter.next();
            System.out.println(stu.name + "身高:" + stu.height + "体重:" + stu.weight);
        }
    }
}

修改后的代码满足以下要求：

1. 两个学生比较大小结果与他们名字字符串的比较结果一致。
2. 有时需要按身高来排，若身高相同则按体重排序。