成绩管理系统java

以下是一个简单的Java成绩管理系统的实现，包括录入学生成绩、查询学生成绩、输出学生按成绩的排名、输出学科的分数四个功能：

import java.util.*;

public class ScoreManagementSystem {
    private Map<String, Map<String, Integer>> scoreMap; // 用Map存储学生成绩信息

    public ScoreManagementSystem() {
        scoreMap = new HashMap<>();
    }

    // 录入成绩
    public void inputScore() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入学生学号：");
        String id = scanner.next();
        System.out.print("请输入学生姓名：");
        String name = scanner.next();
        System.out.print("请输入应用数学成绩：");
        int mathScore = scanner.nextInt();        System.out.print("请输入大学英语成绩：");
        int englishScore = scanner.nextInt();
        System.out.print("请输入Java程序设计成绩：");
        int javaScore = scanner.nextInt();
        System.out.print("请输入计算机应用基础成绩：");
        int computerScore = scanner.nextInt();

        Map<String, Integer> studentScoreMap = new HashMap<>();
        studentScoreMap.put("应用数学", mathScore);
        studentScoreMap.put("大学英语", englishScore);
        studentScoreMap.put("Java程序设计", javaScore);
        studentScoreMap.put("计算机应用基础", computerScore);

        scoreMap.put(id + " " + name, studentScoreMap);
        System.out.println("学生成绩录入成功！");
    }

    // 查询学生成绩
    public void queryScore() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入要查询的学生学号：");
        String id = scanner.next();
        System.out.print("请输入要查询的学生姓名：");
        String name = scanner.next();

        Map<String, Integer> studentScoreMap = scoreMap.get(id + " " + name);
        if (studentScoreMap == null) {
            System.out.println("未找到该学生的成绩信息！");
        } else {
            System.out.println("学生" + name + "的成绩如下：");
            for (Map.Entry<String, Integer> entry : studentScoreMap.entrySet()) {
                System.out.println(entry.getKey() + "：" + entry.getValue());
            }
        }
    }

    // 输出学生按成绩的排名
    public void outputRank() {
        List<Map.Entry<String, Map<String, Integer>>> list = new ArrayList<>(scoreMap.entrySet());
        Collections.sort(list, new Comparator<Map.Entry<String, Map<String, Integer>>>() {
            @Override
            public int compare(Map.Entry<String, Map<String, Integer>> o1, Map.Entry<String, Map<String, Integer>> o2) {
                int sum1 = 0, sum2 = 0;
                for (int score : o1.getValue().values()) {
                    sum1 += score;
                }
                for (int score : o2.getValue().values()) {
                    sum2 += score;
                }
                return sum2 - sum1;
            }
        });

        System.out.println("学生成绩排名如下：");
        for (int i = 0; i < list.size(); i++) {
            System.out.println("第" + (i + 1) + "名：" + list.get(i).getKey());
        }
    }

    // 输出学科的分数
    public void outputSubjectScore() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("请输入要查询的学科名称：");
        String subject = scanner.next();

        System.out.println(subject + "的成绩如下：");
        for (Map<String, Integer> studentScoreMap : scoreMap.values()) {
            System.out.println(studentScoreMap.get(subject));
        }
    }

    public static void main(String[] args) {
        ScoreManagementSystem system = new ScoreManagementSystem();
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请选择要进行的操作：");
            System.out.println("1. 录入成绩");
            System.out.println("2. 查询学生成绩");
            System.out.println("3. 输出学生按成绩的排名");
            System.out.println("4. 输出学科的分数");
            System.out.println("5. 退出系统");
            int choice = scanner.nextInt();
            switch (choice) {
                case 1:
                    system.inputScore();
                    break;
                case 2:
                    system.queryScore();
                    break;
                case 3:
                    system.outputRank();
                    break;
                case 4:
                    system.outputSubjectScore();
                    break;
                case 5:
                    System.exit(0);
                default:
                    System.out.println("输入有误，请重新输入！");
            }
        }
    }
}