public void initGUI()
	{
		// Låt användare välja operation
		// Ta in två heltal 
		System.out.println(" - Choose operation -"
				+ "\n 1. Addition"
				+ "\n 2. Subtraction"
				+ "\n");
		Scanner scanner = new Scanner(System.in);
		String i2 = scanner.nextLine();

		int i = Integer.valueOf(i2);

		System.out.println("First number: ");
		String tal1 = scanner.nextLine();

		System.out.println("\n Second number: ");
		String tal2 = scanner.nextLine();

		switch(i)
		{
		case 1:
			System.out.println(" " + tal1 
					+ "\n + " + tal2
					+ "\n Result: " + performAddition(tal1, tal2));
			break;
		case 2:
			System.out.println(performSubtraction(tal1, tal2));
			break;
		default:
			break;
		}
	}