Java Utililty Methods String Camel Case Format

if (s == null) {
    return null;
s = s.toLowerCase();
StringBuilder sb = new StringBuilder(s.length());
boolean upperCase = false;
for (int i = 0; i < s.length(); i++) {
    char c = s.charAt(i);
...

if (s == null || s.trim().length() == 0) {
    return s;
String[] parts = s.split(" ");
StringBuilder sb = new StringBuilder();
for (String part : parts) {
    String newPart = part.substring(0, 1).toUpperCase() + part.substring(1).toLowerCase();
    sb.append(newPart + " ");
...

if (s == null)
    return null;
if (s.isEmpty() || !Character.isLetter(s.codePointAt(0)))
    return s;
char prefix = s.charAt(0);
prefix = Character.toUpperCase(prefix);
String suffix = s.substring(1);
for (int i = 0; i < suffix.length(); ++i) {
...

String[] parts = s.split("_");
String camelCaseString = "";
for (String part : parts) {
    camelCaseString = camelCaseString + toFirstUpperCase(part);
return camelCaseString;

return toCamelCase(s, DEFAULT_CAMEL_CASE_SPLIT, false);

String[] parts = s.split("_");
if (parts.length == 0) {
    return s.toLowerCase();
String camelCaseString = "";
for (int i = 0; i < parts.length; i++) {
    if (i == 0) {
        camelCaseString = parts[i].toLowerCase();
...

char[] cl = s.toCharArray();
StringBuffer sb = new StringBuffer();
boolean upper = firstCharUppercase;
for (char ch : cl) {
    switch (ch) {
    case '_':
    case '?':
    case ';': 
...

char[] string = s.toCharArray();
int len = 0;
boolean nextUpper = firstUpper;
for (int i = 0; i < string.length; i++) {
    char c = string[i];
    if (c == '_') {
        nextUpper = true;
    } else if (nextUpper) {
...

String[] parts = s.split(separator);
String result = capitalizeFirstPart ? toCapitalCase(parts[0]) : parts[0];
for (int i = 1; i < parts.length; i++) {
    result += toCapitalCase(parts[i]);
return result;

if (nullOrVoid(start)) {
    return "";
} else {
    final StringBuffer sb = new StringBuffer();
    for (String s : start.toLowerCase().split("_")) {
        if (sb.length() > 1) {
            sb.append(Character.toUpperCase(s.charAt(0)));
        } else {
...