How to handle infinite loop caused by invalid input (InputMismatchException) using Scanner

Question

So, I\'m getting stuck with this piece of code:

import java.util.InputMismatchException;
import java.util.Scanner;

public class ConsoleReader {

    Scanner         


        

Answer 1

What I would do is read in the whole line using Scanner.nextLine(). Then create another scanner that reads the returned string.

String line = reader.nextLine();
Scanner sc = new Scanner(line);

This would make your sample function something like this:

  public int readInt(String msg) {
        int num = 0;
        boolean loop = true;

        while (loop) {
            try {
                System.out.println(msg);
                String line = reader.nextLine();
                Scanner sc = new Scanner(line);
                num = sc.nextInt();   
                loop = false;
            } catch (InputMismatchException e) {
                System.out.println("Invalid value!");

            } 
        }
        return num;
    }

This way you have one scanner that gets the input and one that validates it so you don't have to worry about reader caring if they input the correct form of input.