Question

I’m supposed to write a nested for loop that prints the following output:

                   1
                1  2  1
             1  2  4  2  1
          1  2  4  8  4  2  1
       1  2  4  8 16  8  4  2  1
    1  2  4  8 16 32 16  8  4  2  1
 1  2  4  8 16 32 64 32 16  8  4  2  1

I’m supposed to use two methods.

The main method is only supposed to get the number of rows desired from the user.
I’m supposed to write another method called printPyramid that:

1. Has the number of rows
2. Prints a pyramid with that number of rows
3. Returns nothing.

So far, I have:

    import java.util.Scanner;

    public class Pyramid {


    //Getting number of rows, calling printPyramid in main method

    public static void main(String[] args) {

    Scanner input = new Scanner(System.in);

    //Get user input = number of lines to print in a pyramid
    System.out.println("Enter the number of lines to produce: ");
    int numLines = input.nextInt();

    //call method:
    printPyramid();

    }//End of main method

    //Making a new method...

    public static void printPyramid (int numLines) {

    int row;
    int col;

    row = 0;
    col = 0;

        for (row = 1; row <= numLines; row++){
            //print out n-row # of spaces
            for (col = 1; col <= numLines-row; col++){
                System.out.print("  ");
            }

            //print out digits = 2*row-1 # of digits printed
            for (int dig= 1; dig <= 2*row-1; dig++){
                System.out.print(row + "  "); 
            }

        System.out.println();
        }//end of main for loop

    }//end of printPyramid

    }//end of class

I get errors and I can’t figure out how to get it to print out correctly.
I believe the methods are messed up?

Answer 1

Two big errors here. Firstly, ALL with Java are classes so you have to put that main method inside a class. For example:

public class Anything {
    public static void main ...

    public static void printPyramid ...
}

Second one, you have to call the method printPyramid inside the main, because it will not be executed if isn’t called first.

public class Anything {
    public static void main ... {
         ...
         printPyramid (numLines);
         ...
    }

    public static void printPyramid ...
}

I hope this small indications help you.