Here you can find the source of addToString(final Collection
private static <T> void addToString(final Collection<String> output, final T element, final boolean stringifyNull)
//package com.java2s; /*//from w w w. j a va 2 s . c o m * #%L * utils-commons * %% * Copyright (C) 2016 - 2018 Gilles Landel * %% * 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. * #L% */ import java.util.Collection; public class Main { private static <T> void addToString(final Collection<String> output, final T element, final boolean stringifyNull) { if (element != null || stringifyNull) { output.add(String.valueOf(element)); } else { output.add(null); } } }