"Leetcode" Power of Four

Title Link: https://leetcode.com/problems/power-of-four/
Topic:

Given an Integer (signed), write a function to check whether it is a power of 4.

Example:
Given num = +, return true. Given num = 5, return false.

followup: Could solve it without loops/recursion?

Ideas:

Observing 4 powers, it was found that except the highest bit, it was 0, and the number of 0 was even, such as 4=100 16=10000, 8=1000. Otherwise, it's not 4 power.

Algorithm:

public static Boolean ispoweroffour (int num) {          if (num==1)              return true;          if (num==2| | num==3)              return false;          if (num<1)              return false;                    String binary = integer.tobinarystring (num);          Char c[] = Binary.tochararray ();          int count = 0;                    for (int i=1;i<c.length;i++) {//Except the beginning is all 0              if (c[i]!= ' 0 ') {                  return false;              } else{//Statistics 0 of the number of                  count++;              }          }                    if (count!=0&&count%2==0)//has an even number of 0              return true;          else              return false;  }  

"Leetcode" Power of Four