java打印一个菱形

public static void main(String[] args) {int num1 = 4;int num2 = 1;boolean flag = true;for(int i =0;i<9;i++){for(int j = 0;j<num1;j++){System.out.print(" ");}if(flag){num1--;}else{num1++;}for(int k=0;k<num2;k++){System.out.print("*");}if(flag){num2+=2;}else{num2-=2;}System.out.print("\n");if(num1==0)flag = false;}}