Java tutorial
//package com.java2s; //License from project: Open Source License public class Main { private static final String VOID_STRING = ""; private static final String SPACE = " "; private static String addSpaceIfRequired(String value, int index) { if (index == 0) return VOID_STRING; char precedingChar = value.charAt(index - 1); char thisChar = value.charAt(index); if (Character.isLowerCase(precedingChar) && Character.isUpperCase(thisChar) || Character.isLetter(precedingChar) && Character.isDigit(thisChar) || Character.isDigit(precedingChar) && Character.isLetter(thisChar)) { return SPACE; } if (index + 1 == value.length()) return VOID_STRING; char nextChar = value.charAt(index + 1); if (Character.isUpperCase(precedingChar) && Character.isUpperCase(thisChar) && Character.isLowerCase(nextChar)) { return SPACE; } return VOID_STRING; } }