/** * 学生类 * @author student * */public class Student {    private String name;//姓名    private String no;//编号    private double score;//成绩    public Student(String name, String no, double score) {        super();        this.name = name;        this.no = no;        this.score = score;    }    public Student() {        super();    }    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;    }    }

/** * 一个班级多个学生(学生列表) * @author classroom * */public class ClassRoom {    private String no;//班级编号    private List<Student> stuList;//班级列表    private double total;//总分    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;    }    }

/** * 一个Student类，属性name姓名，no编号，score成绩，现在将若干个student对象放入List，请统计出每个班级的总分和平均分 * 面向对象分拣存储 * @author MapDemo * */public class MapDemo {    public static void main(String[] args) {        //1.考试        List<Student> stuList=exam();        //2.分析成绩        Map<String ,ClassRoom> map=count(stuList);        //查看总分 平均分        view(map);    }    /**     * 查询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+"总分："+total+"平均分："+avg);        }    }    /**     * 统计分析     * 1、面向对象     * 2、分拣存储     */    public static Map<String ,ClassRoom> count(List<Student> list){        Map<String ,ClassRoom> map=new HashMap<String,ClassRoom>();        //1.遍历List        for (Student student : list) {            //分拣查出是否存在该编号的班级            String no=student.getNo();//班级编号            double score=student.getScore();//学生成绩            //如果不存在就创建班级            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(student);//放入学生            room.setTotal(room.getTotal()+score);//计算总分        }        return map;    }            /**     * 模拟考试，测试数据放到List中     */    public static List<Student> exam(){        List<Student> list=new ArrayList<Student>();        //存放学生的成绩        list.add(new Student("张三","1班",90));        list.add(new Student("李四","1班",80));        list.add(new Student("王五","1班",60));        list.add(new Student("赵六","2班",90));        list.add(new Student("王大锤","2班",80));        return list;    }}