Keep getting NoSuchElementException with Scanner in Java-CodePudding

I have been learning Java for about three weeks and I'm attempting to write a little vending machine program. For some reason I keep running into a NoSuchElementException through my Scanner, and I've found it is coming from the Item class. I also have my try{} catch{} blocks commented out but I do want to have the ability to catch an InputMismatchException as well. Any help is very much appreciated, I have the code for my Item class below.

    import java.util.*;
    public class Item {
      public Item() {  // class constructor
        System.out.println("Choose an item from the list below!");
        System.out.println("(Enter only the item's number): ");
      }
    
      public void Out() {
        Scanner sc = new Scanner(System.in);
    
        ArrayList<String> optionList = new ArrayList<>();  // collection
        String x = "#1 Coffee Creamer";
        String y = "#2 Black Cold Brew";
        String z = "#3 An Actual Tree";
        optionList.add(x);  // add String x to optionList
        optionList.add(y);  // add String y to optionList
        optionList.add(z);  // add String z to optionList
        System.out.println();
    
        for (String str : optionList) {  // print optionList items
          System.out.println(str);
        }
    
        System.out.println();
        System.out.print("Enter a number: ");  // prompt
    
        int itemNumber = sc.nextInt();  // user's input field
    
        // while (true) {  // catch possible InputMismatchException
        //   try {
        //     itemNumber = sc.nextInt();
        //     break;
        //   } catch (Exception e) {
        //     System.out.println("Enter a valid choice.");
        //     System.out.println("Enter a number: ");
        //   }
        //   sc.nextInt();
        // }
    
        while (itemNumber != 1 && itemNumber != 2 && itemNumber != 3) {
          System.out.println("Enter a valid choice.");
          itemNumber = sc.nextInt();
        } if (itemNumber == 1 || itemNumber == 2 || itemNumber == 3) {
            switch (itemNumber) {
              case 1:
                System.out.println("You chose "   optionList.get(0)   "!");
                break;
              case 2:
                System.out.println("You chose "   optionList.get(1)   "!");
                break;
              case 3:
                System.out.println("You chose "   optionList.get(2)   "!");
                break;
            }
        }
    
        System.out.println();
        sc.close();
      }
    }

CodePudding user response：

try:

        Scanner sc = new Scanner(System.in);


        int itemNumber = 0;
        while (true) {
            try {
                itemNumber = sc.nextInt();
                break;
            } catch (Exception e) {
                System.out.println("Enter a valid choice.");
                System.out.println("Enter a number: ");
                sc.next();
            }
        }

CodePudding user response：

sorry, actually not sure what you want to do but if you want to keep asking for correct number you can define function like

    private static int nextInt(Scanner sc) {
        while (true) {
            try {
                return sc.nextInt();
            } catch (Exception e) {
                System.out.println("Enter a number: ");
                sc.next();
            }
        }
    }

and replace all your calls:

itemNumber = sc.nextInt();

with

itemNumber = nextInt(sc)