Write a program that asks the user to enter the size of a triangle (an integer from 1 to 50) and validate this input. Make sure that your program loops until it receives valid input. Display the triangle by displaying lines of asterisks.

import java.util.Scanner;

public class num1 {

   public static void main(String[] args) {

       Scanner in = new Scanner (System.in);

       int size;

       do{

           System.out.println("Enter the size of the traingle");

           size = in.nextInt();

       }while (size > 50);

           //Using nexted for loop to print the triangle

           for(int i=0; i<size; i++)

           {

               for(int j=0; j<=i; j++)

               {

                   System.out.print("* ");

               }

               System.out.println();

       }

   }

}

Explanation:

Use Scanner class to receive user input

Validate using a do while statement while(num>50) keep prompting the user for a valid input

Use nexted for loops to print the triangle (right-angled triangle call a half pyramid with stars)

difference where there's no picture?