Here you can find the source of toLowerCase(String str)
public static String toLowerCase(String str)
//package com.java2s; /*/*w ww . j a v a 2s . co m*/ * Copyright 2016-2017 the original author or authors. * * 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. */ public class Main { public static String toLowerCase(String str) { if (str == null) { return null; } else { str = str.trim(); if (str.length() == 0) { return null; } else { return str.toLowerCase(); } } } }