The idea is to find the exponent of the given number using the log method of the Math class. If the given number is a power of 4, a number calculated with the power of 4 to this exponent should be equal to the given number.

```
public class Solution {
public boolean isPowerOfFour(int num) {
if(num == 0)
return false;
// Finding the closest (floor) exponent of the number by calculating its log with the base 4
int exponent = (int)(Math.log(num)/Math.log(4));
// Finding the number with 4 to the power of the calculated exponent
int result = (int) Math.pow(4, exponent);
return num == result; // If the given number and the result match, it means the given number is a power of 4.
}
}
```