Homework Java Syntax Problem 7 Count of Bits One

public class Problem_7_CountOfBitsOne {

    public static void main(String[] args) {
    int num=15;
    long count=0;
    //First way
    //System.out.println(Integer.bitCount(num));
    //Second way
    String str= Integer.toBinaryString(num);
    for (int i = 0; i < str.length(); i++) {
        if (str.charAt(i) == '1') {
            count++;

        }
    }
    System.out.println(count);
    }

}