Question

Hello, I need help writing the two methods to print a triangle shape in java. An example of the shape is as follows:

9 8 7 6 5 4 3 
  8 7 6 5 4 3 
    7 6 5 4 3 
      6 5 4 3 
        5 4 3 
          4 3 
            3 
  One method should be defined as "public static void printPattern(int num1, int num2, Boolean ascending)". This method will print a upper-triangle matrix-like layout filled will a sequence of integers between num1 and num2 inclusive. Each subsequent row will contain the postfix of the previous row. For example for num1=3 and num2=9, the pattern should look like the follows. If the ascending is true, the numbers should printed in the ascending order.Another method should be defined as "public static void printPattern(Scanner scnr)". This method will prompt the user for entering thenum1, num2, and ascending, and call the other method to print the pattern. Again, this method must validate the user's input. Notice that this method have the same name as the previous method but has a different set of parameters.

Thank you! I am having so much difficulty!

Answer 1

class Triangle{ //driver class named Triangle
   //printPattern function takes three arguments
   public static void printPattern(int num1,int num2,Boolean ascending){
       int spaces = 0; //spaces of type integer
       if(ascending==false){ //if ascending is false then prints the numbers in lower triangle form
           //loops from num2 to num1 and prints the numbers using inner loop
           for(int i=num2;i>=num1;i--){
               for(int k=0;k<spaces;k++)
                   System.out.print(" ");
               for(int j=i;j>=num1;j--){
                   System.out.printf("%4d",j);
               }
               spaces += 2; //increases the spaces by 2
               System.out.println();
           }
       }else{
           spaces = (num2-num1)*2; //here the number of spaces is evaluated from this expression
           //logic same as above but loops from num1 to num2
           for(int i=num1;i<=num2;i++){
               for(int k=0;k<spaces;k++)
                   System.out.print(" ");
               for(int j=num1;j<=i;j++){
                   System.out.printf("%4d",j);
               }
               spaces -= 2; //decreases spaces by 2.
               System.out.println();
           }
       }
   }
   //main mehtod
   public static void main(String[] args) {
       printPattern(3,9,false); //calls the printPattern method by passing ascending parameter value as false
       printPattern(1,10,true); //calls the printPattern method by passing ascending parameter value as true
   }
}

//output screenshots

//any query, post in the comment section