list.add(new Student(“Tom”, 18, 100, “class05”));  

list.add(new Student(“Jerry”, 22, 70, “class04”)); 

list.add(new Student(“Owen”, 25, 90, “class05”)); 

list.add(new Student(“Jim”, 30,80 , “class05”)); 

list.add(new Student(“Steve”, 28, 66, “class06”));

 list.add(new Student(“Kevin”, 24, 100, “class04”)); 

在这个list 的基础上，完成下列要求： 

1） 计算所有学生的平均年龄

2） 计算各个班级的平均分 

package com.hanqi.test;public class Student {     private String name;          private int age;          private int score;      private String classNum;            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 getScore() {        return score;    }    public void setScore(int score) {        this.score = score;    }    public String getClassNum() {        return classNum;    }    public void setClassNum(String classNum) {        this.classNum = classNum;    }    public Student() {        super();            }    public Student(String name, int age, int score, String classNum) {        super();        this.name = name;        this.age = age;        this.score = score;        this.classNum = classNum;    }    }

package com.hanqi.test;import java.util.ArrayList;import java.util.List;public class TestStudent {    public static void main(String[] args) {                List
     
        list = new ArrayList<>();                list.add(new Student("Tom",18,100,"class05"));        list.add(new Student("Jerry",22,70,"class04"));        list.add(new Student("Owen",25,90,"class05"));        list.add(new Student("Jim",30,80,"class05"));        list.add(new Student("Steve",28,66,"class06"));        list.add(new Student("Kevin",24,100,"class04"));                        int sum=0;        for(int i=0;i