Diamond of star

class Main {
    public static void main(String[] args) {
        int n = 5; // controls height (half diamond)

        // Upper part
        for (int i = 1; i <= n; i++) {
            // spaces
            for (int j = 1; j <= n - i; j++) {
                System.out.print(" ");
            }
            // stars
            for (int j = 1; j <= 2*i - 1; j++) {
                System.out.print("*");
            }
            System.out.println();
        }

        // Lower part
        for (int i = n - 1; i >= 1; i--) {
            // spaces
            for (int j = 1; j <= n - i; j++) {
                System.out.print(" ");
            }
            // stars
            for (int j = 1; j <= 2*i - 1; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
    }
}