How to determine when last integer has been entered? Java

Question

I currently have to enter a letter to stop the while loop and print out the number list. Is there a better way to determine when the last int has been entered?

` Scanner scanner = new Scanner(System.in);
            System.out.println("Enter a sequence of integer values" +
                    " to be sent to the server");
            List<Integer> numberList = new ArrayList<Integer>();
            while(scanner.hasNextInt()) {
                numberList.add(scanner.nextInt());
            }
            System.out.println(numberList);
            os.write(String.valueOf(numberList));
            scanner.close();`

Answer 1

Do it as follows:

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

public class Program {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter a sequence of integer values to be sent to the server (x to terminate)");
        List<Integer> numberList = new ArrayList<Integer>();
        String[] data = scanner.nextLine().split(" ");
        int i = 0;
        while (i < data.length && data[i].matches("\\d+")) {// The regex \d+ matches only integers
            numberList.add(Integer.parseInt(data[i]));
            i++;
        }
        System.out.println(numberList);
    }
}

A sample run:

Enter a sequence of integer values to be sent to the server (x to terminate)
10 20 30 X
[10, 20, 30]

Also, do not close Scanner for System.in as it also closes System.in as well.