Java：ECC（纠错码）库？

Question

是否有一个众所周知的 Java 的 ECC（纠错码）库（例如 Reed-Solomon）实现，具有友好的开源许可（非 GPL）？

Answer 1

zxing

Apache 许可证（不确定这是否符合您对友好的定义）我也不确定是否如此算众所周知（谷歌知道这一点，“java Reed-Solomon”没有 2 个结果）？

Answer 2

我已经为 Plank 等人编写的 JErasure 库实现了 Java 包装器。 。

如果您不介意本机依赖性，那么 JErasure 是一个很好的选择（如果不是最好的） 在有人将 JErasure 移植到 Java 之前，您将不得不简化性能，因为在处理较大的数据块时，zxing 中的实现速度并不那么快。

我已将代码放在 GitHub 上： https://github.com/jvandertil/Jerasure

Answer 3

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Scanner;

class Student {
    private String ID;
    private String name;
    private int age;
    private List<Course> enrolledCourses;

    public Student(String ID, String name, int age) {
        this.ID = ID;
        this.name = name;
        this.age = age;
        this.enrolledCourses = new ArrayList<>();
    }

    public void enrollCourse(Course course) {
        enrolledCourses.add(course);
    }

    public void viewCourseDetails() {
        System.out.println("Enrolled courses:");
        for (Course course : enrolledCourses) {
            System.out.println(course.getName());
        }
    }

    public void viewGrades() {
        System.out.println("Grades for enrolled courses:");
        for (Course course : enrolledCourses) {
            System.out.println("Course: " + course.getName() + ", Grade: " + course.getGrade(this));
        }
    }
}

class Instructor {
    private String ID;
    private String name;
    private int age;
    private List<Course> taughtCourses;

    public Instructor(String ID, String name, int age) {
        this.ID = ID;
        this.name = name;
        this.age = age;
        this.taughtCourses = new ArrayList<>();
    }

    public void assignCourse(Course course) {
        taughtCourses.add(course);
    }

    public void viewEnrolledStudents(Course course) {
        List<Student> enrolledStudents = course.getEnrolledStudents();
        System.out.println("Enrolled students in " + course.getName() + ":");
        for (Student student : enrolledStudents) {
            System.out.println(student.getName());
        }
    }
}

class Course {
    private String courseCode;
    private String name;
    private Instructor instructor;
    private List<Student> enrolledStudents;
    private Map<Student, Integer> grades;

    public Course(String courseCode, String name, Instructor instructor) {
        this.courseCode = courseCode;
        this.name = name;
        this.instructor = instructor;
        this.enrolledStudents = new ArrayList<>();
        this.grades = new HashMap<>();
    }

    public void addStudent(Student student) {
        enrolledStudents.add(student);
    }

    public void setInstructor(Instructor instructor) {
        this.instructor = instructor;
    }

    public void addGrade(Student student, int grade) {
        grades.put(student, grade);
    }

    public int getGrade(Student student) {
        Integer grade = grades.get(student);
        return (grade != null) ? grade : -1; // Return -1 if grade not found
    }

    public double calculateAverageGrade() {
        int totalGrades = 0;
        for (int grade : grades.values()) {
            totalGrades += grade;
        }
        return (grades.size() > 0) ? (double) totalGrades / grades.size() : 0;
    }

    public String getName() {
        return name;
    }

    public List<Student> getEnrolledStudents() {
        return enrolledStudents;
    }
}

class StudentManagementSystem {
    private List<Student> students;
    private List<Instructor> instructors;
    private List<Course> courses;
    private Scanner scanner;

    public StudentManagementSystem() {
        students = new ArrayList<>();
        instructors = new ArrayList<>();
        courses = new ArrayList<>();
        scanner = new Scanner(System.in);
    }

    public void addStudent() {
        System.out.print("Enter student ID: ");
        String ID = scanner.nextLine();
        System.out.print("Enter student name: ");
        String name = scanner.nextLine();
        System.out.print("Enter student age: ");
        int age = Integer.parseInt(scanner.nextLine());

        Student student = new Student(ID, name, age);
        students.add(student);
        System.out.println("Student added successfully.");
    }

    public void addInstructor() {
        System.out.print("Enter instructor ID: ");
        String ID = scanner.nextLine();
        System.out.print("Enter instructor name: ");
        String name = scanner.nextLine();
        System.out.print("Enter instructor age: ");
        int age = Integer.parseInt(scanner.nextLine());

        Instructor instructor = new Instructor(ID, name, age);
        instructors.add(instructor);
        System.out.println("Instructor added successfully.");
    }

    public void enrollStudentInCourse() {
        System.out.print("Enter student ID: ");
        String studentID = scanner.nextLine();
        System.out.print("Enter course code: ");
        String courseCode = scanner.nextLine();

        Student student = getStudentByID(studentID);
        Course course = getCourseByCode(courseCode);

        if (student != null && course != null) {
            student.enrollCourse(course);
            course.addStudent(student);
            System.out.println("Student enrolled in the course successfully.");
        } else {
            System.out.println("Invalid student ID or course code.");
        }
    }

    public void assignInstructorToCourse() {
        System.out.print("Enter instructor ID: ");
        String instructorID = scanner.nextLine();
        System.out.print("Enter course code: ");
        String courseCode = scanner.nextLine();

        Instructor instructor = getInstructorByID(instructorID);
        Course course = getCourseByCode(courseCode);

        if (instructor != null && course != null) {
            instructor.assignCourse(course);
            course.setInstructor(instructor);
            System.out.println("Instructor assigned to the course successfully.");
        } else {
            System.out.println("Invalid instructor ID or course code.");
        }
    }

    public void viewCourseDetails() {
        System.out.print("Enter course code: ");
        String courseCode = scanner.nextLine();

        Course course = getCourseByCode(courseCode);

        if (course != null) {
            System.out.println("Course: " + course.getName());
            System.out.println("Instructor: " + course.getInstructor().getName());
            System.out.println("Average Grade: " + course.calculateAverageGrade());
        } else {
            System.out.println("Course not found.");
        }
    }

    public void viewEnrolledStudents() {
        System.out.print("Enter course code: ");
        String courseCode = scanner.nextLine();

        Course course = getCourseByCode(courseCode);

        if (course != null) {
            course.getInstructor().viewEnrolledStudents(course);
        } else {
            System.out.println("Course not found.");
        }
    }

    public Student getStudentByID(String studentID) {
        for (Student student : students) {
            if (student.getID().equals(studentID)) {
                return student;
            }
        }
        return null;
    }

    public Instructor getInstructorByID(String instructorID) {
        for (Instructor instructor : instructors) {
            if (instructor.getID().equals(instructorID)) {
                return instructor;
            }
        }
        return null;
    }

    public Course getCourseByCode(String courseCode) {
        for (Course course : courses) {
            if (course.getCourseCode().equals(courseCode)) {
                return course;
            }
        }
        return null;
    }

    public void run() {
        while (true) {
            System.out.println("\n***** Student Management System Menu *****");
            System.out.println("1. Add a new student");
            System.out.println("2. Add a new instructor");
            System.out.println("3. Enroll a student in a course");
            System.out.println("4. Assign an instructor to a course");
            System.out.println("5. View course details and average grades");
            System.out.println("6. View the list of students enrolled in a course");
            System.out.println("0. Exit");

            System.out.print("Enter your choice: ");
            int choice = Integer.parseInt(scanner.nextLine());

            switch (choice) {
                case 1:
                    addStudent();
                    break;
                case 2:
                    addInstructor();
                    break;
                case 3:
                    enrollStudentInCourse();
                    break;
                case 4:
                    assignInstructorToCourse();
                    break;
                case 5:
                    viewCourseDetails();
                    break;
                case 6:
                    viewEnrolledStudents();
                    break;
                case 0:
                    System.out.println("Exiting Student Management System. Goodbye!");
                    System.exit(0);
                    break;
                default:
                    System.out.println("Invalid choice. Please try again.");
            }
        }
    }

    public static void main(String[] args) {
        StudentManagementSystem system = new StudentManagementSystem();
        system.run();
    }
}