import java.util.ArrayList;
import java.util.Scanner;

public class NumberList
{
	private ArrayList<Integer> numbers;

	public NumberList()
	{
		numbers = new ArrayList<Integer>();
	}

	public void menu()
	{
		Scanner scanner = new Scanner(System.in);

		while (true)
		{
			System.out.println("\nMenu Options\n");
			System.out.println("(1) add a number to the list");
			System.out.println("(2) sum the number in the list");
			System.out.println("(3) calculate the average");
			System.out.println("(4) quit");

			System.out.print("\nYour Seclection: ");
			int choice = scanner.nextInt();

			if( choice == 1 ) {
				System.out.print("Please enter an integer: ");
				int input = scanner.nextInt();
				numbers.add( new Integer(input) );
				System.out.println("You add " + input + " to the list");
			}
			else if( choice == 2 ) {
				System.out.println("Summation = " + sum() );
			}
			else if( choice == 3 ) {
				System.out.println("Average = " + average() );
			}
			else if( choice == 4 ) {
				break;
			}
			else
				System.out.println("Invalid choice");
		}
	}

	public int sum()
	{
		int result = 0;

		for( Integer number : numbers ) {
			result += number.intValue();
		}

		return result;
	}

	public double average()
	{
		return (double)sum()/numbers.size();
	}
}