用java 打印菱形

public class testthree {
public static void main(String[] args) {
testthree t = new testthree();
t.test();
}

private static void test() {
int d = 0;
int f = 4;
int x = 0;
int y = 6;
for (int j = 0; j < 4; j++) {
f = f - 1;
for (int i = 0; i < f; i++) {
System.out.print(" ");
}
d = d + 2;
for (int i = 1; i < d; i++) {
System.out.print("*");
}
System.out.println();
}
for (int j = 0; j < 4; j++) {
x = x + 1;
for (int i = 0; i < x; i++) {
System.out.print(" ");
}
y = y - 2;
for (int i = 0; i <= y; i++) {
System.out.print("*");
}
System.out.println();
}
}
}