Right Angles

 import java.util.Scanner;
    
    public class rig
    {
        
        public static void main( String[] args ) 
        {
            
            Scanner keyboard = new Scanner(System.in);
            
            int side1, side2, side3;
            
            System.out.println( "Enter three integers:" );
            System.out.print( "Side 1: " );
            side1 = keyboard.nextInt();
            
            while ( side1 <= 0 ) 
            {
                System.out.println( "Come on, a side can't be negative." );
                System.out.print( "Side 1: " );
                side1 = keyboard.nextInt();
            }
            
            System.out.print( "Side 2: " );
            side2 = keyboard.nextInt();
            
            while ( side2 < side1 ) 
            {
                System.out.println( side2 + " is smaller than " + side1 + ", try again." );
                System.out.print( "Side 2: " );
                side2 = keyboard.nextInt();
            }
            
            System.out.print( "Side 3: " );
            side3 = keyboard.nextInt();
            
            while ( side3 < side2 ) 
            {
                System.out.println( side3 + " is smaller than " + side2 + ", try again." );
                System.out.print( "Side 3: " );
                side3 = keyboard.nextInt();
            }
            
            System.out.println( "Your three sides are " + side1 + ", " + side2 + ", and " + side3 + "." );
            double right = Math.sqrt( side1 * side1 + side2 * side2 );
            
            if ( right == side3 )
            {
                System.out.println( "Yup, those sides make a right triangle!" );
            }
            
            else 
            {
                System.out.println( "Not a right triangle! Sorry" );
            }
            
        }
    }
    

Picture of the output