Day14作业 三、编程题 写一个Student类，属性：名字，年龄，分数，班级 (注意分包)

三、编程题
写一个Student类，属性：名字，年龄，分数，班级 (注意分包)

写一个测试类：创建一个集合，里面装6个学生(有三个班级class01，class02，class03)
例如：list.add(new Student(“Tom”, 18, 100,“class01”)); 

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.stu;

public class Stu
{
private String name,grades;//姓名,班级
private int age,score;//年龄,分数
public Stu(){}
public Stu(String name, String grades, int age, int score)
{
super();
this.name = name;
this.grades = grades;
this.age = age;
this.score = score;
}
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
public String getGrades()
{
return grades;
}
public void setGrades(String grades)
{
this.grades = grades;
}
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 void show(){
System.out.println("姓名:"+getName()+",班级:"+getGrades()+",年龄:"+getAge()+",分数:"+getScore());
}

}

package Day14;

import java.util.List;
import java.util.ArrayList;
import com.stu.Stu;

public class HomeWork_03
{

public static void main(String[] args)
{
List co = new ArrayList();
co.add(new Stu("小张", "class01", 21, 80));
co.add(new Stu("小涛", "class01", 23, 85));
co.add(new Stu("小聪", "class02", 22, 65));
co.add(new Stu("小噢", "class02", 27, 80));
co.add(new Stu("小平", "class03", 20, 85));
co.add(new Stu("小区", "class03", 18, 75));

int ageAver = AgeAver(co);
System.out.println("平均年龄:" + ageAver);

int ScoreAver = ScoreAver(co);
System.out.println("平均分数:" + ScoreAver);
}

public static int AgeAver(List co)
{
int ageSum = 0;// 设置个和
int ageAver;
for (Object obj : co)
{
Stu stu = (Stu) obj;
/*
* 【向下转型】：将父类对象引用强制转为子类类型的过程;
* 语法: 子类类型 引用 = (子类类型)父类对象引用;
*/
ageSum += stu.getAge();//遍历相加得出总数
}
ageAver = ageSum / co.size();//总数/人数=平均数,131/6~=21;
return ageAver;
}

public static int ScoreAver(List co)
{
int scoreSum = 0;
int scoreAver;
for (Object obj : co)
{
Stu stu = (Stu) obj;
scoreSum += stu.getScore();
}
scoreAver = scoreSum / co.size();
return scoreAver;

}
}