Here you can find the source of nullToEmpty(List
public static <T> List<T> nullToEmpty(List<T> list)
//package com.java2s; /*/*ww w . j av a2s . c om*/ * * * Licensed to the Apache Software Foundation (ASF) under one or more * * contributor license agreements. See the NOTICE file distributed with * * this work for additional information regarding copyright ownership. * * The ASF licenses this file to You 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.Collections; import java.util.List; import java.util.Map; import java.util.Set; public class Main { public static <T> List<T> nullToEmpty(List<T> list) { return list == null ? Collections.emptyList() : list; } public static <T> Set<T> nullToEmpty(Set<T> set) { return set == null ? Collections.emptySet() : set; } public static <K, V> Map<K, V> nullToEmpty(Map<K, V> map) { return map == null ? Collections.emptyMap() : map; } }