爪哇；当我遇到一个输入时，我会得到“Exception in thread”main“java.util.NoSuchelementException”

Question

我正在制作一个非常基本的数据库管理程序，我有一个名称和值扫描器在一个类（account.java）中运行良好，

public static void createNewAccount() {

    Scanner newScan = new Scanner(System.in);
    System.out.print("Enter name: ");
    String inputName = newScan.nextLine();
    name = inputName;
    System.out.print("Enter the initial value: ");
    double inputBalance = newScan.nextInt();
    System.out.println("... successfully created new account.");

    keyScan.close();


    Account newAccount = new Account(inputName, inputBalance);

}

...
Scanner in = new Scanner(System.in);

    Account.createAccount();
//Debugging statement #1 here works fine, can access other Class
do{
        /*
        Menu Options
        */
        System.out.println(">> Select your option (1-6)");
        choice = in.nextInt();

//Debugging statement #2 here doesn't display, this is where the error hits.

    switch (choice) {
         ... Cases
        }

>> Select your option (1-6)
Exception in thread "main" java.util.NoSuchElementException
        at java.util.Scanner.throwFor(Unknown Source)
        at java.util.Scanner.next(Unknown Source)
        at java.util.Scanner.nextInt(Unknown Source)
        at java.util.Scanner.nextInt(Unknown Source)
        at Management.main(Management.java:30)

我很困惑为什么会发生这种情况，因为我有另一个扫描仪，工作得很好。

Answer 1

当关闭扫描程序时，它也会关闭基础的InputStream。因此，如果在程序的早期使用system.in创建扫描程序，然后关闭该扫描程序，它将关闭system.in。

一旦关闭了inputstream，就不能再从中读取它，尝试这样做将导致NoSuchelementException。