用Java编写一个题库管理系统，要求录入题目功能中的题目录入一道采用文件的形式保存，且功能为1.列出所有试题信息，2.按科目查询 ，3.添加试题，4.删除试题，5.退出系统。界面在控制台输出，写出源码

好的，下面是一个Java题库管理系统的源码，实现了列出所有试题信息、按科目查询、添加试题、删除试题、退出系统的功能：

Question类：

public class Question {
    private String subject; // 科目
    private String content; // 题目内容
    private String[] options; // 选项
    private int answer; // 答案

    public Question(String subject, String content, String[] options, int answer) {
        this.subject = subject;
        this.content = content;
        this.options = options;
        this.answer = answer;
    }

    public String getSubject() {
        return subject;
    }

    public String getContent() {
        return content;
    }

    public String[] getOptions() {
        return options;
    }

    public int getAnswer() {
        return answer;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("Subject: ").append(subject).append("\n");
        sb.append(content).append("\n");
        for (int i = 0; i < options.length; i++) {
            sb.append((char)('A' + i)).append(". ").append(options[i]).append("\n");
        }
        sb.append("Answer: ").append((char)('A' + answer));
        return sb.toString();
    }
}

QuestionManager类：

import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class QuestionManager {
    private static final String FILE_NAME = "questions.txt"; // 题目文件名
    private List<Question> questions; // 题库

    public QuestionManager() {
        questions = new ArrayList<>();
        loadQuestionsFromFile();
    }

    // 从文件中加载所有题目
    private void loadQuestionsFromFile() {
        try (BufferedReader reader = new BufferedReader(new FileReader(FILE_NAME))) {
            String line;
            while ((line = reader.readLine()) != null) {
                String[] parts = line.split(",");
                String subject = parts[0];
                String content = parts[1];
                String[] options = {parts[2], parts[3], parts[4], parts[5]};
                int answer = Integer.parseInt(parts[6]);
                Question question = new Question(subject, content, options, answer);
                questions.add(question);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 保存题目到文件中
    private void saveQuestionsToFile() {
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(FILE_NAME))) {
            for (Question question : questions) {
                writer.write(question.getSubject() + ","
                        + question.getContent() + ","
                        + question.getOptions()[0] + ","
                        + question.getOptions()[1] + ","
                        + question.getOptions()[2] + ","
                        + question.getOptions()[3] + ","
                        + question.getAnswer());
                writer.newLine();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    // 列出所有试题信息
    public void listAllQuestions() {
        for (Question question : questions) {
            System.out.println(question);
            System.out.println("--------------------");
        }
    }

    // 按科目查询
    public void searchBySubject(String subject) {
        for (Question question : questions) {
            if (question.getSubject().equals(subject)) {
                System.out.println(question);
                System.out.println("--------------------");
            }
        }
    }

    // 添加试题
    public void addQuestion() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Subject: ");
        String subject = scanner.nextLine();
        System.out.print("Content: ");
        String content = scanner.nextLine();
        String[] options = new String[4];
        for (int i = 0; i < 4; i++) {
            System.out.print((char)('A' + i) + ": ");
            options[i] = scanner.nextLine();
        }
        System.out.print("Answer: ");
        int answer = scanner.nextLine().charAt(0) - 'A';
        Question question = new Question(subject, content, options, answer);
        questions.add(question);
        saveQuestionsToFile();
    }

    // 删除试题
    public void deleteQuestion() {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Subject: ");
        String subject = scanner.nextLine();
        System.out.print("Content: ");
        String content = scanner.nextLine();
        for (int i = 0; i < questions.size(); i++) {
            Question question = questions.get(i);
            if (question.getSubject().equals(subject) && question.getContent().equals(content)) {
                questions.remove(i);
                saveQuestionsToFile();
                System.out.println("Question deleted.");
                return;
            }
        }
        System.out.println("Question not found.");
    }
}

Main类：

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        QuestionManager questionManager = new QuestionManager();

        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("Enter your choice:");
            System.out.println("1. List all questions");
            System.out.println("2. Search by subject");
            System.out.println("3. Add question");
            System.out.println("4. Delete question");
            System.out.println("5. Quit");
            int choice = scanner.nextInt();
            scanner.nextLine();

            switch (choice) {
                case 1:
                    questionManager.listAllQuestions();
                    break;
                case 2:
                    System.out.print("Subject: ");
                    String subject = scanner.nextLine();
                    questionManager.searchBySubject(subject);
                    break;
                case 3:
                    questionManager.addQuestion();
                    break;
                case 4:
                    questionManager.deleteQuestion();
                    break;
                case 5:
                    System.exit(0);
                default:
                    System.out.println("Invalid choice.");
            }
        }
    }
}

以上代码实现了一个简单的控制台题库管理系统，包括列出所有试题信息、按科目查询、添加试题、删除试题、退出系统的功能。您可以根据需求进行修改和完善。注意，在本示例中，题目信息以逗号分隔保存在文件中，您也可以选择其他方式进行存储。