Christmas Tree - Java

once upon a time, I went to this comp sci competition, and there was this problem:

Take an user-input, which is an integer indicating the number of levels in the tree.
and the output should look like this:

My java code after the jump :)

• the tree will print 1, 3, 5..... number of *
• you need to format it so the tree will alignment in the middle, i just use spaces here
• the stump needs to be right in the middle

import static java.lang.System.*;

import java.io.*;

import java.util.*;

public class Tree

{

    public static void main(String[] args)

    {

        Scanner scan = new Scanner(in);

        out.print("please enter a number: ");

        int temp = scan.nextInt();

        int x = (temp-1)*2 +1;

        int y = x/2;  // calculate how many spaces you need to print before the stump

        int z = 1;  // initial #of * you need to print
        for(int i=0; i<temp; i++) //determines how many lines you print

        {

            for(int j=0; j<=y; j++) //determines how many spaces you print

            {

                out.print(" ");

            }

            for(int k = 0; k<z; k++) // determines how many * you print

            {

                out.print("*");

            }

            out.println();

            y--;

            z+=2; //add 2 for the 1,3,5,7 increment

        }

        for(int i =0; i<=x/2; i++) //prints the spaces you need until you reach the middle

        {

            out.print(" ");

        }

        out.println("*"); // the stump!

    }

}

hope this helps people who have similiar assignments :)

i'm not really good at explaining things, so i apologize if this is confusing