用java编程：输出一个用*号组成的菱形!* *** ***** *** *

public class Cat {
public static void main(String[] args) {

int num = 2;
drawDiamond(num);
}
private static void drawDiamond(int num) {
for (int i = 0; i < num; i++) {
for (int j = num - i; j > 0; j--) {
System.out.print(" ");
}
for (int z = 0; z = 0; i--) {
for (int j = i; j < num; j++) {
System.out.print(" ");
}
for (int z = 0; z