Here you can find the source of toStringList(Collection
public static String toStringList(Collection<String> strings, String separator)
//package com.java2s; /*//from w w w. j a va2 s.c o m * Copyright 2014 Bernd Vogt and others. * * 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. */ import java.util.Arrays; import java.util.Collection; public class Main { public static String toStringList(String[] strings, String separator) { if (strings != null) { return toStringList(Arrays.asList(strings), separator); } return null; } public static String toStringList(Collection<String> strings, String separator) { if (strings != null) { final StringBuilder sb = new StringBuilder(); for (String string : strings) { sb.append(separator); sb.append(string); } if (sb.length() > 0) { sb.delete(0, separator.length()); } return sb.toString(); } return null; } }