public class Student {

    private int id;

    private String school;

    private String major;

    private String name;

    public Student()

    {

    }

    public Student(int id,String school,String major,String name)

    {

        this.id = id;

        this.school = school;

        this.major = major;

        this.name = name;

    }

    public String toString(){

        return this.id +"   "+this.school +"  "+ this.name+"  "+this.major;

    }

    public int getId() {

        return id;

    }

    public void setId(int id) {

        this.id = id;

    }

    public String getSchool() {

        return school;

    }

    public void setSchool(String school) {

        this.school = school;

    }

    public String getMajor() {

        return major;

    }

    public void setMajor(String major) {

        this.major = major;

    }

    public String getName() {

        return name;

    }

    public void setName(String name) {

        this.name = name;

    }

}

import java.io.*;

import java.util.HashMap;

import java.util.Iterator;

import java.util.LinkedList;

import java.util.Map;

import java.util.Set;

public class PrintTheNo1 {

    public static void main(String [] args) throws IOException

    {

        try{

            LinkedList<Student> stuList =getStuList();

            HashMap<Integer,Double> map = getSumScoreOfStudent();

            getTopStu(stuList,map);

        }catch(IOException io)

        {

            System.out.println("出错了呀！"+io);

        }

    }

    //读取info文件

    public static LinkedList<Student> getStuList() throws IOException

    {

        String oneLine;

        try{

            FileReader a = new FileReader("D:\\NewPro\\Files\\info.txt");

            BufferedReader br = new BufferedReader(a);

            int line = 0;

            LinkedList<Student> stuList = new LinkedList<Student>();

            while((oneLine = br.readLine() )!= null)

            {

                //从文件的第二行开始读取数据

                line++;

                if(line == 1) continue;

                else

                {

                    String[] info = oneLine.split("    ");

                    Student stu = new Student(Integer.parseInt(info[0]),(String)info[1],(String)info[2],(String)info[3]);

                    stuList.add(stu);

                }

            }

            for(Student s:stuList)

                System.out.println(s.toString());

            br.close();

            return stuList;

        }catch(IOException io)

        {

            System.out.println("error@"+io);

            return null;

        }

    }

    //求各个学生的总分

    public static HashMap<Integer,Double>  getSumScoreOfStudent() throws IOException

    {

        HashMap<Integer,Double> map = new HashMap<Integer,Double>();

        String oneLine;

        try{

            FileReader a = new FileReader("D:\\NewPro\\Files\\score.txt");

            BufferedReader br = new BufferedReader(a);

            int line = 0;

            double sum = 0;

            while((oneLine = br.readLine() )!= null)

            {

                ++line;

                if(line == 1) continue;

                else

                {

                    String [] info = oneLine.split("    ");

                    int id = Integer.parseInt(info[0]);

                    if(map.containsKey(id))

                    {

                        sum = map.get(id)+Double.parseDouble(info[2]);

                        map.put(id,sum);

                    }

                    else

                        map.put(id,Double.parseDouble(info[2]));

                }

            }

            return map;

        }catch(IOException io)

        {

            System.out.println("error in score.txt"+io);

            return null;

        }

    }

    //各个专业第一名的学生

    public static void getTopStu(LinkedList<Student> stuList,HashMap<Integer,Double> map)

    {

        Student s = new Student();

        int id =0;

        double score = 0;

        double maxScore = 0;

        String major;

        //MajorAndScore保存专业--最高分

        HashMap<String,Double> MajorAndScore = new HashMap<String,Double>();

        //result保存 专业--学号，然后遍历result，根据result的学号值找到Student信息，保存到topStudent链表中。

        HashMap<String,Integer> result  = new HashMap<String,Integer>();

        LinkedList<Student> topStudent = new LinkedList<Student>();

        if(stuList.size() == 0 || map.size() ==0 )

            return;

        for(int i=0;i<stuList.size();i++)

        {

            s = stuList.get(i);

            id =s.getId();

            score = map.get(id);//拿到该学生的总分

            major = s.getMajor();

            if(map.containsKey(id) )

            {

                if(MajorAndScore.containsKey(major) && score > maxScore)

                    //如果已经有major.且当前学生的总分更大一些，把更大的分数加进去

                {

                    maxScore = score;

                    MajorAndScore.put(major,maxScore);

                    result.put(major,id);

                }

                else if(!MajorAndScore.containsKey(major))

                    //如果不存在major key

                    {

                        MajorAndScore.put(major,score);

                        result.put(major,id);

                    }

                else

                    {

                        map.remove(id);

                    }

            }

        }

        @SuppressWarnings("rawtypes")

        Set st = result.entrySet();

        Iterator it =st.iterator();

        while(it.hasNext())

        {

            Map.Entry entry = (Map.Entry)it.next();

            topStudent.add(getById(stuList,(Integer)entry.getValue()));

        }

        System.out.println( "各专业第一名是： ");

        for(int i=0;i<topStudent.size();i++)

        {

            System.out.println(topStudent.get(i).toString());

        }

    }    

    //根据id找到学生信息

    private static Student getById(LinkedList<Student> stuList,int id)

    {

        for(int i=0;i<stuList.size();i++)

        {

            if(stuList.get(i).getId() == id)

            {

                return stuList.get(i);

            }

        }

        return null;

    }

}