Моя Java-программа отображает ошибку: IOException: Поток закрыт - но у меня нет вызова close () для этого потока

Question

Это моя основная функция:

package com.ss.lms;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    // if we close this once... it seems to be closed forever...
    public static BufferedReader stdinBufReader = new BufferedReader(new InputStreamReader(System.in));

    // our main function
    public static void main(String[] args) {
        MenuInterface.stdinBufReader = stdinBufReader;
        while (MenuInterface.displayMenu()) { }

        /*try { stdinBufReader.close(); }
        catch (IOException e) { e.printStackTrace(); }*/
    }
}

Я прошел класс MenuInterface и выполнил текстовый поиск по слову «закрыть», и нигде там ничего не закрылось.

Здесь происходит ошибка:

package com.ss.lms;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
    // if we close this once... it seems to be closed forever...
    public static BufferedReader stdinBufReader = new BufferedReader(new InputStreamReader(System.in));

    // our main function
    public static void main(String[] args) {
        MenuInterface.stdinBufReader = stdinBufReader;
        while (MenuInterface.displayMenu()) { }

        /*try { stdinBufReader.close(); }
        catch (IOException e) { e.printStackTrace(); }*/
    }

}

Это трассировка стека:

Would you like to perform another operation? (Y/N): java.io.IOException: Stream closed
    at java.base/java.io.BufferedInputStream.getBufIfOpen(BufferedInputStream.java:169)
    at java.base/java.io.BufferedInputStream.read(BufferedInputStream.java:335)
    at java.base/sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:297)
    at java.base/sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:339)
    at java.base/sun.nio.cs.StreamDecoder.read(StreamDecoder.java:188)
    at java.base/java.io.InputStreamReader.read(InputStreamReader.java:185)
    at java.base/java.io.BufferedReader.fill(BufferedReader.java:161)
    at java.base/java.io.BufferedReader.readLine(BufferedReader.java:326)
    at java.base/java.io.BufferedReader.readLine(BufferedReader.java:392)
    at com.ss.lms.MenuInterface.promptContinue(MenuInterface.java:108)
    at com.ss.lms.MenuInterface.displayMenu(MenuInterface.java:47)
    at com.ss.lms.Main.main(Main.java:14)
Exception in thread "main" java.lang.NullPointerException
    at com.ss.lms.MenuInterface.isYesOrNo(MenuInterface.java:121)
    at com.ss.lms.MenuInterface.promptContinue(MenuInterface.java:111)
    at com.ss.lms.MenuInterface.displayMenu(MenuInterface.java:47)
    at com.ss.lms.Main.main(Main.java:14)

Вот весь файл для MenuInterface.java:

package com.ss.lms;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

import com.ss.lms.controllers.AuthorController;

public class MenuInterface {
    // our list of entities
    public static String[] entities = {"author", "book", "publisher"};

    // maps a character to an action.
    // e.g. 'c' => "create"
    public static Map<String, String> crudOptions = new HashMap<String, String>();

    // if we close this once... it seems to be closed forever...
    public static BufferedReader stdinBufReader;

    public static Boolean displayMenu() {
        String selectedModel;
        String selectedAction;

        try {
            selectedModel = promptModel();
            selectedAction = promptCRUDAction();
            switch (selectedModel) {
                case "author":
                    switch (selectedAction) {
                        case "create":
                            AuthorController.create();
                            break;
                        case "read":
                            System.out.print("Enter author ID for retrieval: ");
                            Integer authorId = Integer.parseInt(stdinBufReader.readLine());
                            AuthorController.read(authorId);
                            break;
                    }
                    break;
            }
        } catch (IOException e1) {
            e1.printStackTrace();
        }

        return promptContinue();
    }

    // Prompt the user for which entity they want to perform actions with.
    public static String promptModel() throws IOException {
        String selectedEntity;
        int selectionNum = 0;

        // prompt the user
        System.out.println("1 - Author");
        System.out.println("2 - Book");
        System.out.println("3 - Publisher");
        System.out.print("\nChoose an entity: ");

        selectionNum = Integer.parseInt(stdinBufReader.readLine());

        selectedEntity = entities[selectionNum - 1];

        System.out.println("\nYou selected: " + selectedEntity + "\n");
        return selectedEntity;
    }

    // Prompts the user for a character input, returns a string representation
    // of the action they want to perform. E.g. "create", "read"...
    public static String promptCRUDAction() throws IOException {
        String selectedChar = null;
        String selectedAction;

        crudOptions.put("c", "create");
        crudOptions.put("r", "read");
        crudOptions.put("u", "update");
        crudOptions.put("d", "destroy");

        do {
            System.out.println("(C)reate");
            System.out.println("(R)ead");
            System.out.println("(U)pdate");
            System.out.println("(D)estroy");
            System.out.print("\nChoose an action: ");

            try { selectedChar = stdinBufReader.readLine(); }
            catch (IOException e) { e.printStackTrace(); }

            selectedAction = crudOptions.get(selectedChar);
            if (selectedAction == null) {
                System.out.println("\nInvalid Option. Try again.\n");
            }

        } while (selectedAction == null);

        System.out.println("\nYou selected: " + selectedAction);

        return selectedAction;
    }

    public static Boolean promptContinue() {
        String userInput = null;
        Boolean continueSelected = null;
        do {
            System.out.print("Would you like to perform another operation? (Y/N): ");

            // keep getting weird errors saying the Stream is closed when it isn't
            try {  userInput = stdinBufReader.readLine().toLowerCase(); }
            catch (IOException e) { e.printStackTrace(); }

            if (!isYesOrNo(userInput)) {
                System.out.println("Please enter either Y or N.");
            }

            continueSelected = userInput == "y" ? true : false;
        } while (!isYesOrNo(userInput));
        return continueSelected;
    }

    public static Boolean isYesOrNo(String userInput) {
        return userInput.toLowerCase() == "y" || userInput.toLowerCase() == "n";
    }
}