请将下面程序补充完整。 public class PowerCalc{ public static void main(String[]args){ double x=5.0; System. out. println(x+'to the power 4 is'+power(x, 4)); System. out. println('7. 5 to the power 5 is'+power(7.5, 5)); System. out. println('7.5 to the power 0 is'+power(7.5, 0)); System. out. println('10 to the power -2 is'+power(10, -2)); } static double【 】 (double x, int n){ if(n＞1) return x * power(x, n-1); else if(n＜0) return 1.0/power(x, -n); else return n==0 ? 1.0:x; } }