How to implement a cancel statement if no data entered

I'm still learning at programming and really need some help, I need to make a program with a lot of features and most of it is done, but I'm having difficulty creating a particular line. I'm using a while loop to get the user to input numbers to calculate largest, smallest, as well as sums with a random generated number. I need to program a way that if the user enters the exit statement, -99, before any other data is entered, it will say "You have entered no numbers." and quit the program. Any help would be awesome, and below will be my program code.

import java.util.Scanner;
import java.util.Random;

public class LargestSmallest
{
public static void main(String [] args)
{
    //identifier declarations
    int number;
    int numberend = -99;
    int largest = Integer.MIN_VALUE;
    int smallest = Integer.MAX_VALUE;
    int number1;
    int sum1;
    int sum2;


    //create a Scanner object to read from the keyboard & input 
    Scanner input = new Scanner(System.in);


    //create a random object
    Random randomNumbers = new Random();

    //get one random number
    number1 = randomNumbers.nextInt(9); 

    //display prompts and get input
    System.out.println("Enter an integer, or -99 to quit:");

    //loop for number input
    while ((number = input.nextInt()) != numberend) {
        System.out.println("Enter an integer, or -99 to quit:");

        //largest & smallest number sorting

        if (number > largest) {
        largest = number;
        }
        if (number < smallest) {
        smallest = number;
        }


    }
    //calculate final sums
    sum1 = number1 + largest;
    sum2 = number1 + smallest;

    //final statements
    System.out.println("Largest:" + largest);
    System.out.println("Smallest:" + smallest);
    System.out.println("Random:" + number1);
    System.out.println("Largest + Random:" + sum1);
    System.out.println("Smallest + Random:" + sum2);

  }
}