LeetCode/problems/java/number-of-1-bits.java

public class Solution {
    public int hammingWeight(int n) {
        int bits = 0;

        for (int i = 0; i < 32; ++i) {
            if ((n & (1 << i)) != 0) {
                ++bits;
            }
        }

        return bits;
    }
}