Here you can find the source of bitCount(String s)
public static final int bitCount(String s)
//package com.java2s; /*//ww w . j a va 2 s . c om * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ public class Main { public static final int bitCount(String s) { int total = 0; for (int i = 0; i < s.length(); i++) { total += char2int(s.charAt(i)); } return total; } public static final int char2int(char c) { return (int) (c - '0'); } }