所以这是一项艰巨的工作。我正在制作一个基于文本的信息亭，人们可以按作者，标题等进行搜索。现在我很难使用自助服务终端添加书籍。我可以添加所有信息，但在我输入每本书的信息后，我得到一个No Such Element异常。不确定这意味着什么，任何帮助都会受到赞赏。
import java.util.Scanner;
import java.util.ArrayList;
public class Books{
public static void main(String[] args) {
//Part 1: Initialize the MIS
//Part 1.1: Open Scanner
Scanner keyboard = new Scanner(System.in);
//Part 1.2: Build a store
Store newstore = new Store();
//Part 1.3: Build an array of books
final int MAX_NUM_BOOKS = 500;
Books[] list_book = new Books[MAX_NUM_BOOKS];
//Part 1.4: Prompt for the initial book count
System.out.println("How many books do we have?");
int bookcount = keyboard.nextInt();
//Part 1.5: Builds the books
for(int i=0; i<bookcount; i++) list_book[i] = new Books();
//Part 1.6: Create switch menu
boolean exit = false;
while(!exit){
System.out.println("Please make a selection: ");
System.out.println("To search by Title (0)");
System.out.println("To search by Author's Last name (1)");
System.out.println("To search by Author's First name (2)");
System.out.println("To search by ISBN (3)");
System.out.println("To add a book to the inventory (4)");
System.out.println("To exit (5)");
int option = keyboard.nextInt();
switch(option){
case 0:System.out.print("Please enter the title of the book you are looking for: ");
String title = keyboard.next();
results(Book.TitleSearch(title));
break;
case 1: System.out.print("Please enter the last name of the author you are looking for: ");
String auth_last = keyboard.next();
results(Book.Auth_LastSearch(auth_last));
break;
case 2:System.out.print("Please enter the first name of the author you are looking for: ");
String auth_first = keyboard.next();
results(Book.Auth_FirstSearch(auth_first));
break;
case 3:System.out.print("Please enter the ISBN of the book you are looking for: ");
String ISBN = keyboard.next();
results(Book.ISBNSearch(ISBN));
break;
case 4:addBook(newstore);
break;
case 5: exit=true;
}//switch
}//while
//Part :Close Input
keyboard.close();
}
//Part 2: Add Books to the Store
private static void addBook(Store newstore) {
Scanner keyboard = new Scanner(System.in);
System.out.print("Enter title of the book: ");
String title = keyboard.next();
System.out.print("Enter Author's first name: ");
String auth_first_nam = keyboard.next();
System.out.print("Enter Author's last name: ");
String auth_last_nam = keyboard.next();
System.out.print("Enter the ISBN: ");
String isbn = keyboard.next();
Book book = new Book(title, auth_first_nam, auth_last_nam, isbn);
Store.addBook(book);
keyboard.close();
}
private static String results(String titleSearch) {
return Book.output();
}
}
//Build each individual book
class Book{
private static String title;
private static String auth_first_nam;
private static String auth_last_nam;
private static String isbn;
private static String bookinfo;
public Book(Scanner keyboard){
System.out.println("Enter the book Title: ");
title=keyboard.next();
System.out.println("Enter in the Author's Last Name: ");
auth_last_nam=keyboard.next();
System.out.println("Enter in the Author's First Name: ");
auth_first_nam=keyboard.next();
System.out.println("Enter the ISBN number: ");
isbn=keyboard.next();
}
public Book(String title, String auth_first_nam, String auth_last_nam, String isbn) {
}
public static String output() {
bookinfo=(title+" by " + auth_first_nam + " " + auth_last_nam + ". ISBN: " +isbn);
return bookinfo;
}
public static String ISBNSearch(String iSBN2) {
return isbn;
}
public static String Auth_FirstSearch(String auth_first) {
return auth_first_nam;
}
public static String Auth_LastSearch(String auth_last) {
return auth_last_nam;
}
public static String TitleSearch(String title2) {
return title;
}
public String getTitle() {
return title;
}
public String GetAuthorLast(){
return auth_last_nam;
}
public String GetAuthorFirst(){
return auth_last_nam;
}
public String getISBN() {
return isbn;
}
}
class Store{
private static ArrayList<Book> books;
private static Book book;
public Store(){
books = new ArrayList<Book>();
}
public static void addBook(Book Book){
if(book==null){
System.out.println("I'm sorry, but you didn't enter in any information.");
return;
}
else{
books.add(Book);
}
}
public Book getTitle(String title){
for(int i=0;i<books.size(); i++)
{
if(books.get(i).getTitle().equals(title))
{
book=books.get(i);
}
}
return book;
}
public ArrayList<Book> findAutLast(String aut_last_nam)
{
ArrayList<Book> found = new ArrayList<Book>();
for(int i=0; i<books.size(); i++)
{
Book current = books.get(i);
if(current.GetAuthorLast().indexOf(aut_last_nam) >=0)
{
found.add(current);
}
}
return found;
}
public ArrayList<Book> findTitle(String title){
ArrayList<Book> found = new ArrayList<Book>();
for(int i=0; i<books.size();i++)
{
Book current = books.get(i);
if (current.getTitle().indexOf(title) >=0)
{
found.add(current);
}
}
return found;
}
public ArrayList<Book> findISBN(String isbn)
{
ArrayList<Book> found = new ArrayList<Book>();
for(int i=0; i<books.size(); i++)
{
Book current = books.get(i);
if(current.getISBN().indexOf(isbn) >=0)
{
found.add(current);
}
}
return found;
}
}
对不起，有一些死密码和松散的目标仍然被捆绑。我对以前从未见过的No Element非常好奇。在案例4中使用Switch后，它发生在第35行。
答案 0 :(得分：1)
问题实际上在这个方法中：
private static void addBook(Store newstore) {
...
keyboard.close();
}
关闭keyboard的{{1}}个实例。
您调用Scanner的循环正在使用addBook扫描程序，下次循环调用keyboard失败，因为扫描程序已关闭。
我通过运行代码推断出这一点，并观察以下异常：
keyboard.nextInt()值得注意的是，第36行是
Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:838)
at java.util.Scanner.next(Scanner.java:1461)
at java.util.Scanner.nextInt(Scanner.java:2091)
at java.util.Scanner.nextInt(Scanner.java:2050)
at Books.main(Books.java:36)
我在运行选项4（添加一本书）后才点击此异常。
如果您从int option = keyboard.nextInt();
方法中删除keyboard.close()，您的程序将不会再崩溃。
我不希望您的程序正常运行，因为您还有其他一些错误（误用addBook()字段和方法），但它不会再抛出static。
作为提示（因为这似乎是家庭作业），我在你的程序中看到的其他问题：
NoSuchElementException的静态字段（因此您希望在图书上定义的属性不会与对象保持一致）Book（类似于上文）Book中设置字段（并在不适当的构造函数中重复使用addBook中的代码）Book代替您可能想要的内容，这是Books[]（或者由于Book[] ArrayList<Book> books，这可能是无关紧要的
答案 1 :(得分：0)
虽然很难分辨，因为你没有提供堆栈跟踪，但我可以看到一个问题，即何时访问ArrayList中的元素。通过盯着你的代码很难说，但我会先修复这个
private static String title;
private static String auth_first_nam;
private static String auth_last_nam;
private static String isbn;
private static String bookinfo;
您拥有static所有这些字段。这意味着，对于您创建并添加Book个图书的每个ArrayList，每个图书都将具有完全相同的title, auth_first_nan, auth_last_nam, isbn, and bookinfo。这可能会导致程序出现问题。虽然可能不会导致NoSuchElementException，但我仍然可以解决这个问题。
例如，如果您首先添加标题为“StackOverflow”的Book，则添加标题为“StackExchange”的Book ，第一个Book的{{1}}也变为“StackExchange”。这意味着，如果您尝试通过title “StackOverflow”访问图书，您将永远找不到它
将所有字段更改为不包含title
static