Console program in Java to sum two integer numbers, verifying that the user actually input integer numbers

Sum.java

import java.util.Scanner;

public class Sum {

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

	public static void main(String[] args) {

		int firstNumber;
		int secondNumber;
		int sum;
		boolean validNumber = false;
		
		System.out.println("\nWelcome to the program to sum two integer numbers.");

		firstNumber = requestNumber(validNumber);

		secondNumber = requestNumber(validNumber);
	
		sc.close();

		sum = firstNumber + secondNumber;
		
		System.out.println("\nThe sum of " + firstNumber + " and " + secondNumber + " is " + sum + "\n");

	}

	// This method verifies that the user actually input an integer number, and if so it returns that valid number
	private static int requestNumber(boolean validNumber) {
		int numberToReturn = 0;
		while (!validNumber) {
			System.out.println("\nPlease insert an integer number:");
			if (sc.hasNextInt()) {
				validNumber = true;
				numberToReturn = sc.nextInt();
				System.out.println("\nYou have entered " + numberToReturn);
			} else {
				System.out.println("\nError. Please insert a valid integer number.");
			}
			sc.nextLine();
		}
		return numberToReturn;
	}

}