Java Utililty Methods String Camel Case to Snake Case

List of utility methods to do String Camel Case to Snake Case

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Description

The list of methods to do String Camel Case to Snake Case are organized into topic(s).

Method

StringcamelToSnake(final String camelStr)
camel To Snake 
String ret = camelStr.replaceAll("([A-Z]+)([A-Z][a-z])", "$1_$2").replaceAll("([a-z])([A-Z])", "$1_$2");
return ret.toLowerCase();
StringcamelToSnake(String camel, boolean upper)
Converts camel case string (lower or upper/Pascal) to snake case, for example 'helloWorld' or 'HelloWorld' -> 'hello_world'. 
StringBuilder stringBuilder = new StringBuilder();
for (char c : camel.toCharArray()) {
    char nc = upper ? Character.toUpperCase(c) : Character.toLowerCase(c);
    if (Character.isUpperCase(c)) {
        stringBuilder.append('_').append(nc);
    } else {
        stringBuilder.append(nc);
return stringBuilder.toString();
StringcamelToSnake(String value)
camel To Snake 
final char[] name = value.toCharArray();
final StringBuilder builder = new StringBuilder();
for (int i = 0; i < name.length; i++) {
    if (Character.isUpperCase(name[i]) || name[i] == '.' || name[i] == '$') {
        if (i != 0 && name[i - 1] != '.' && name[i - 1] != '$') {
            builder.append('_');
        if (name[i] != '.' && name[i] != '$') {
...
StringcamelToSnakeCase(final String camelCase)
converts ruby to camel case 
if (camelCase == null || camelCase.isEmpty()) {
    return "";
return camelCase.replaceAll("\\B([A-Z])", "_$1").toLowerCase();
StringcamelToSnakeCase(String camelcase)
camel To Snake Case 
return camelcase.replaceAll("([A-Z][a-z])", "_$1");
StringcamelToSnakeCase(String string)
Converts a string from CamelCase to snake_case. 
switch (string) {
case "IO":
    return "io";
case "OS":
    return "os";
case "MD5":
    return "md5";
default:
...
StringcamelToSneakCase(String name)
camel To Sneak Case 
StringBuilder sb = new StringBuilder();
int cur = 0;
while (cur < name.length()) {
    char c = name.charAt(cur);
    if (!Character.isUpperCase(c)) {
        sb.append(c);
        cur++;
        continue;
...
StringcamelToUpperSnake(String camel)
Converts camel case string (lower or upper/Pascal) to upper snake case, for example 'helloWorld' or 'HelloWorld' -> 'HELLO_WORLD'. 
return camelToSnake(camel, true);