Java tutorial
//package com.java2s; /** * Copyright (C) 2010-2016 eBusiness Information, Excilys Group * * Licensed under the Apache License, Version 2.0 (the "License"); you may not * use this file except in compliance with the License. You may obtain a copy of * the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed To in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations under * the License. */ import java.util.ArrayList; import java.util.List; import java.util.regex.Matcher; import java.util.regex.Pattern; public class Main { private static final Pattern PATTERN = Pattern.compile("([A-Z]|[a-z])[a-z0-9]*"); public static String camelCaseToSnakeCase(String camelCase) { List<String> tokens = new ArrayList<>(); Matcher matcher = PATTERN.matcher(camelCase); String acronym = ""; while (matcher.find()) { String found = matcher.group(); if (found.matches("^[A-Z]$")) { acronym += found; } else { if (acronym.length() > 0) { // we have an acronym to add before we continue tokens.add(acronym); acronym = ""; } tokens.add(found.toLowerCase()); } } if (acronym.length() > 0) { tokens.add(acronym); } if (tokens.size() > 0) { StringBuilder sb = new StringBuilder(tokens.remove(0)); for (String s : tokens) { sb.append("_").append(s); } return sb.toString(); } else { return camelCase; } } }