How to close Scanner when two methods from 2 different classes use a Scanner Object?

Question

I have a menu for a Bank in the main class the Scanner is initialized in the irrelevant above code

Main

while(true) {
    Scanner kbs = new Scanner(System.in);

            
    try {
        Menu.mainMenu();
        int selection = kbs.nextInt();

         
         try {
                if(selection == 1) {
                    dublin.customerWithdraw();
                    
                }
                else if(selection == 0) {
                    break;
                }
             }
             catch(NoSuchElementException e) {
                 System.out.println("That is not a option");
                 
                 
             }
    }
    catch(InputMismatchException e) {
         System.out.println("That is not a option");

    }

}

The `dublin.customerWithdraw(); calls a method in bank which also uses a Scanner

Bank

//Customer Withdraw
public void customerWithdraw() {
    
    Scanner kb = new Scanner(System.in);
    
    //List of Customers to choose from
    //Selecting the Id of Customer
    //Finding the Customer from the ArrayList
    viewCustomers();
    
    System.out.println("Enter Customers Passport Number:");
    String custPastport = kb.nextLine();
    
    Customer customerFind = findCustomer(custPastport);
    
    if(customerFind != null){
        //Check to make sure the amount entered for the withdraw request is valid
        try { 
            
            //Calling Customer scanArmChip method to scan composed ArmChip Id 
            // if they are correct proceed with withdraw
            if(customerFind.scanID()) {
                System.out.println("Enter withdraw amount: ");
                int withdraw = kb.nextInt();
                
                //Calling the Customer withdraw method to minus the wanted amount 
                customerFind.withdraw(withdraw); 
  
                System.out.println(customerFind);
            }
            else {
                System.out.println("Person Id does not match Arm Id call police!!!");
            }
            
        } 
        catch(NullPointerException e){
                System.out.println("This ID is not valid"); 
        }
    }
    else {
        System.out.println("The passport number entered is incorrect");
    }

    //If I close the scanner here I get a error 
        
}

The error message displayed is

Exception in thread "main" java.util.NoSuchElementException
    at java.base/java.util.Scanner.throwFor(Scanner.java:937)
    at java.base/java.util.Scanner.next(Scanner.java:1594)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2258)
    at java.base/java.util.Scanner.nextInt(Scanner.java:2212)
    at Main.main(Main.java:51)

I have done some research and found out that because I close the Scanner in the infinite loop it can not reopen even if I close it in the outside method.

I need to have it closeed in both classes and im not sure how?

The Menu works fine and executes the methods when I just choose not to close the Scanner object and the loop will present the user with the option to choose again.

If I close the object in the Main class or in the Bank class that is when I get the error.

If you're using `Scanner` with `System.in`, just don't close it. Like the classic joke, *"Doctor, it hurts when I do this!"* - *"Well, stop doing it then."* — kaya3, Jan 27 '20 at 23:38
Does the not cause any security risks or considered poor programming? I am only trying to close it as in eclipse it prompts me to — Liam, Jan 27 '20 at 23:39
Eclipse is wrong in this case. There is almost never a need to close `System.in`; for learner-programmers, I would just say never close `System.in`. — kaya3, Jan 27 '20 at 23:42
There are also ways to [close a scanner without closing System.in](https://stackoverflow.com/questions/14962082/close-scanner-without-closing-system-in) — azurefrog, Jan 27 '20 at 23:43
@azurefrog The way you do that is by writing a class with an empty `close` method that does nothing. There is no benefit to doing that if it's your own code that calls `.close()`; just change your code so it doesn't call `close()`. Closing the Scanner has no useful effect other than closing the underlying InputStream, so if you don't want to do that, just don't call `.close()`. — kaya3, Jan 28 '20 at 04:30

How to close Scanner when two methods from 2 different classes use a Scanner Object?

0 Answers0