Here you can find the source of putLowerNotNull(Map
public static <V> void putLowerNotNull(Map<String, V> m, String k, V v)
//package com.java2s; /*/*from ww w . ja v a2s .c o m*/ * This file is part of the Spider Web Framework. * * The Spider Web Framework is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * The Spider Web Framework is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with the Spider Web Framework. If not, see <http://www.gnu.org/licenses/>. */ import java.util.Map; public class Main { /** Put a lowercase version of k in the map if it is non-null */ public static <V> void putLowerNotNull(Map<String, V> m, String k, V v) { if (k != null) m.put(k.toLowerCase(), v); } }