Week 1: Types, condition clauses and loops/17. Number triangle

Write a program that asks the user to enter an integer.
The program will then print a number triangle corresponding to the integer number according to the example printouts shown below.
Example output:
Give a number: 4
1
12
123
1234



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



public class Test{
    public static void main(String[] args){
        final Random r = new Random();
        
        Scanner reader= new Scanner(System.in);
        System.out.print("Give a number: ");
        int user_num = Integer.valueOf(reader.nextLine());
        
        for (int row=1; row<=user_num; row++) {
            
            String rowprintout = "";
            for (int col=1; col<=row; col++) {
              rowprintout = rowprintout + col;
            }

            System.out.println(rowprintout);
        }
        
    }
}





Testing with input 4
Give a number: 4
1
12
123
1234

Testing with input 6
Give a number: 6
1
12
123
1234
12345
123456

Testing with input 7
Give a number: 7
1
12
123
1234
12345
123456
1234567

Testing with input 5
Give a number: 5
1
12
123
1234
12345

Testing with input 1
Give a number: 1
1