开发环境: Windows 11 IDEA 2021.3.3

需求:

package com.it.neu;import java.util.ArrayList;import java.util.Scanner;import static java.time.Clock.system;class Student { //创建学生类 private String Stu_name; private String Stu_id; public Student(String id, String name) { this.Stu_id = id; this.Stu_name = name; } public String getStu_name() { return Stu_name; } public void setStu_name(String stu_name) { Stu_name = stu_name; } public String getStu_id() { return Stu_id; } public void setStu_id(String stu_id) { Stu_id = stu_id; }}class Course { //创建课程类 private String Course_name; public Course(String course_name) { this.Course_name = course_name; } public String getCourse_name() { return Course_name; } public void setCourse_name(String course_name) { Course_name = course_name; }}class Score { //创建成绩表类 private int rank; //序号--代表进入成绩管理系统的位次 private Student student; private Course course; private double grade; //代表成绩的意思 public Score(int rank, Student student, Course course, double grade) { this.rank = rank; this.student = student; this.course = course; this.grade = grade; } public int getRank() { return rank; } public void setRank(int rank) { this.rank = rank; } public Student getStudent() { return student; } public void setStudent(Student student) { this.student = student; } public Course getCourse() { return course; } public void setCourse(Course course) { this.course = course; } public double getGrade() { return grade; } public void setGrade(double grade) { this.grade = grade; }}class StudentScoreManager { //创建一个成绩管理的类 private ArrayList<Score> scores;//新建一个类的数组 public StudentScoreManager() { scores = new ArrayList<>(); } //初始化这个类成员数组 //通过调用manager.addScore(score)方法，将score对象添加到scores列表中。 // 如果这个方法成功执行并返回true，那么score对象就会被添加到scores列表中。 public boolean addScore(Score score) { return scores.add(score); // 将score对象添加到列表中，并返回添加操作的结果 } //删除学生成绩的功能，某一门课//同时判断是否删除成功 public boolean removeScore(Student student, Course course) { for (Score score : scores) { if (score.getStudent().getStu_id().equals(student.getStu_id()) && score.getStudent().getStu_name().equals(student.getStu_name()) && score.getCourse().getCourse_name().equals(course.getCourse_name())) { scores.remove(score); return true; } } return false; } //实现修改成学生成绩功能 public boolean changeScore(Student student, Course course, double newGrade) { for (Score score : scores) { if (score.getStudent().getStu_id().equals(student.getStu_id()) && score.getStudent().getStu_name().equals(student.getStu_name()) && score.getCourse().getCourse_name().equals(course.getCourse_name())) { score.setGrade(newGrade); return true; } } return false; } //实现计算某门课平均成绩的功能 public double getAverageGrade(Course course) { double sum = 0; int count = 0; for (Score score : scores) { if (score.getCourse().getCourse_name().equals(course.getCourse_name())) { //找到这门课了 sum += score.getGrade(); count++; } } return count > 0 ? sum / count : 0; } //查找某门课的最高成绩 public double getHighesrGrade(Course course) { //某门课的最高成绩 double higest = 0; for (Score score : scores) { if (score.getCourse().getCourse_name().equals(course.getCourse_name()) && score.getGrade() > higest) { higest = score.getGrade(); } } return higest; } //查找某门课的最低成绩 public double getLowestGrade(Course course) { double lowest = 100; for (Score score : scores) { if (score.getCourse().getCourse_name().equals(course.getCourse_name()) && score.getGrade() < lowest) { lowest = score.getGrade(); } } return lowest; } //实现成绩排序功能 public void sortScores() { scores.sort((s1, s2) -> Double.compare(s2.getGrade(), s1.getGrade())); } public void printScores() { sortScores(); for (Score score : scores) { System.out.println(score.getRank() + " " + score.getStudent().getStu_id() + " " + score.getStudent().getStu_name() + " " + score.getCourse().getCourse_name() + " " + score.getGrade()); } } public boolean printfixScores(Student student) { int count = 0; for (Score score : scores) { if (score.getStudent().getStu_id().equals(student.getStu_id()) && score.getStudent().getStu_name().equals(student.getStu_name())) { System.out.println(score.getCourse().getCourse_name() + "的成绩是" + score.getGrade()); count++; } } return count > 0 ? true : false; } //获取scores类list的长度 public int getScoresLength() { return scores.size(); }}public class Work { public static void printmenu() { System.out.println("---------------------------------------"); System.out.println("欢迎使用学生成绩管理系统"); System.out.println("---------------------------------------"); System.out.println("1. 添加学生成绩"); System.out.println("2. 删除学生成绩"); System.out.println("3. 修改学生成绩"); System.out.println("4. 计算课程平均-最高-最低-成绩"); System.out.println("5. 查询学生成绩"); System.out.println("6. 对成绩进行排序并打印所有成绩"); System.out.println("0. 退出系统"); System.out.println("---------------------------------------"); System.out.print("请输入操作序号："); } public static void main(String[] args) { Scanner scanner = new Scanner(System.in); StudentScoreManager manager = new StudentScoreManager(); while (true) { printmenu(); int opeartion = scanner.nextInt(); if (opeartion < 0 || opeartion > 6) { System.out.println("没有这个选项，请重新选择！"); continue; } scanner.nextLine(); switch (opeartion) { case 1: { System.out.println("您正在使用功能一：添加学生成绩"); System.out.println("---------------------------------------"); System.out.println("请输入学生学号："); String id = scanner.nextLine(); System.out.println("请输入学生姓名："); String name = scanner.nextLine(); System.out.println("请输入课程名称："); String courseName = scanner.nextLine(); System.out.println("请输入成绩："); double grade = scanner.nextDouble(); //新建临时类来存储输入的数据 Student student = new Student(id, name); Course course = new Course(courseName); Score score = new Score(manager.getScoresLength() + 1, student, course, grade); //将这个临时的数据塞入,manager这个类的scores-list中, if (manager.addScore(score)) { System.out.println("添加成绩数据成功！"); } else { System.out.println("添加成绩数据失败！"); } // 等待用户按下回车键继续执行 System.out.println("按下回车键继续..."); scanner.nextLine(); break; } case 2: { System.out.println("您正在使用功能二：删除学生成绩"); System.out.println("---------------------------------------"); System.out.println("请输入学生学号："); String id = scanner.nextLine(); System.out.println("请输入学生姓名："); String name = scanner.nextLine(); System.out.println("请输入课程名称："); String courseName = scanner.nextLine(); Student student = new Student(id, name); Course course = new Course(courseName); if (manager.removeScore(student, course)) { System.out.println("删除学生成绩成功！"); } else { System.out.println("删除学生成绩失败！没有找到此人"); } // 等待用户按下回车键继续执行 System.out.println("按下回车键继续..."); scanner.nextLine(); break; } case 3: { System.out.println("您正在使用功能三：修改学生成绩"); System.out.println("---------------------------------------"); System.out.println("请输入学生学号："); String id = scanner.nextLine(); System.out.println("请输入学生姓名："); String name = scanner.nextLine(); System.out.println("请输入课程名称："); String courseName = scanner.nextLine(); System.out.println("请输入新的成绩："); double newGrade = scanner.nextDouble(); Student student = new Student(id, name); Course course = new Course(courseName); if (manager.changeScore(student, course, newGrade)) { System.out.println("修改学生成绩成功！"); } else { System.out.println("修改学生成绩失败！没有找到此人"); } break; } case 4: { System.out.println("您正在使用功能四：计算课程平均-最高-最低-成绩"); System.out.println("---------------------------------------"); System.out.println("请输入课程名称："); String courseName = scanner.nextLine(); Course course = new Course(courseName); double average = manager.getAverageGrade(course); double higest = manager.getHighesrGrade(course); double lowest = manager.getLowestGrade(course); System.out.println(courseName + "的平均成绩为：" + average); System.out.println(courseName + "的最高成绩为：" + higest); System.out.println(courseName + "的最低成绩为：" + lowest); // 等待用户按下回车键继续执行 System.out.println("按下回车键继续..."); scanner.nextLine(); break; } case 5: { System.out.println("您正在使用功能五：查询学生成绩"); System.out.println("---------------------------------------"); System.out.println("请输入学生学号："); String id = scanner.nextLine(); System.out.println("请输入学生姓名："); String name = scanner.nextLine(); Student student = new Student(id, name); if (manager.printfixScores(student)) { //判断的同时可以调用 } else { System.out.println("没有找到此人"); } // 等待用户按下回车键继续执行 System.out.println("按下回车键继续..."); scanner.nextLine(); break; } case 6: { System.out.println("您正在使用功能六：对成绩进行排序并打印所有成绩"); System.out.println("---------------------------------------"); manager.printScores(); // 等待用户按下回车键继续执行 System.out.println("按下回车键继续..."); scanner.nextLine(); break; } } } }}