Java中面向对象的分拣存储

Student.java

package yzhou.map;

/**
 * 学生类
 *
 *
 * @author 洋
 *
 */
public class Student
{
    private String name;
    private String no;
    private double score;
    public Student()
    {

    }
    public Student(String name, String no, double score)
    {
        super();
        this.name = name;
        this.no = no;
        this.score = score;
    }
    public String getName()
    {
        return name;
    }
    public void setName(String name)
    {
        this.name = name;
    }
    public String getNo()
    {
        return no;
    }
    public void setNo(String no)
    {
        this.no = no;
    }
    public double getScore()
    {
        return score;
    }
    public void setScore(double score)
    {
        this.score = score;
    }

}

ClassRoom.java

package yzhou.map;

import java.util.ArrayList;
import java.util.List;

/**
 * 一个班级 多个学生
 * @author 洋
 *
 */
public class ClassRoom
{
    private String no;
    private List<Student> stuList;
    private double total;

    public ClassRoom()
    {
        stuList = new ArrayList<Student>();
    }

    public ClassRoom(String no)
    {
        this();
        this.no = no;
    }

    public ClassRoom(String no, List<Student> stuList, double total)
    {
        super();
        this.no = no;
        this.stuList = stuList;
        this.total = total;
    }

    public String getNo()
    {
        return no;
    }

    public void setNo(String no)
    {
        this.no = no;
    }

    public List<Student> getStuList()
    {
        return stuList;
    }

    public void setStuList(List<Student> stuList)
    {
        this.stuList = stuList;
    }

    public double getTotal()
    {
        return total;
    }

    public void setTotal(double total)
    {
        this.total = total;
    }

}

MapDemo03.java

package yzhou.map;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;

/**
 *
 * 面向对象+分解存储
 * @author 洋
 *
 */
public class MapDemo03
{
    public static void main(String[] args)
    {
        List<Student> stuList = exam();
        Map<String, ClassRoom> map = count(stuList);
        view(map);
    }

    /*
     * 查看每个班的总分和平均分    --》遍历map
     * */
    public static void view(Map<String, ClassRoom> map)
    {
        Set<String> keys = map.keySet();
        //获取迭代器对象
        Iterator<String> keysIt = keys.iterator();
        //先判断
        while(keysIt.hasNext()){
            //在获取
            String no = keysIt.next();
            ClassRoom room = map.get(no);
            //查看总分 计算平均分
            double total = room.getTotal();
            double avg = total/room.getStuList().size();
            System.out.println(no+"--->"+total+"-->"+avg);
        }

    }

    /*
     * 统计分析
     * */
    public static Map<String, ClassRoom> count(List<Student> list){
        Map<String, ClassRoom> map = new HashMap<String,ClassRoom>();
        //1.遍历
        for(Student stu:list)
        {
            //分拣查看是否存在， 该编号的班级
            String no = stu.getNo();
            double score = stu.getScore();
            //如果不存在 ，创建班级
            ClassRoom room  = map.get(no);
            if(null==room)
            {
                room = new ClassRoom(no);
                map.put(no, room);
            }

            //存在，放入学生
            room.getStuList().add(stu);
            room.setTotal(room.getTotal()+score);
        }
        return map;
    }

    /*
     * 模拟考试 测试数据到List 中
     * */

    public static List<Student> exam(){
        List<Student> list = new ArrayList<Student>();
        //存放学生成绩
        list.add(new Student("yzhou01","a",80));
        list.add(new Student("yzhou02","a",80));
        list.add(new Student("yzhou03","a",80));
        list.add(new Student("yzhou04","b",80));
        list.add(new Student("yzhou05","b",80));
        list.add(new Student("yzhou06","b",80));
        return list;
    };

}