Here you can find the source of split(String s)
private static String split(String s)
//package com.java2s; /*-/*from w w w . j av a 2 s .co m*/ * ==========================License-Start============================= * stargraph-model * -------------------------------------------------------------------- * Copyright (C) 2017 Lambda^3 * -------------------------------------------------------------------- * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. * ==========================License-End=============================== */ import java.util.StringJoiner; public class Main { private static final String RE_CAMELCASE_OR_UNDERSCORE = "(?<!(^|[A-Z]))(?=[A-Z])|(?<!^)(?=[A-Z][a-z])|_"; private static String split(String s) { if (s == null || s.isEmpty()) { return s; } StringJoiner joiner = new StringJoiner(" "); for (String word : s.split(RE_CAMELCASE_OR_UNDERSCORE)) { if (!word.isEmpty()) { joiner.add(word.trim()); } } return joiner.toString(); } }