Here you can find the source of collectionToString(Collection
public static <T> String collectionToString(Collection<T> collection)
//package com.java2s; /*//from www. ja v a 2 s .co m * Tencent is pleased to support the open source community by making Tinker available. * * Copyright (C) 2016 THL A29 Limited, a Tencent company. All rights reserved. * * Licensed under the BSD 3-Clause License (the "License"); you may not use this file except in * compliance with the License. You may obtain a copy of the License at * * https://opensource.org/licenses/BSD-3-Clause * * 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.Collection; public class Main { public static <T> String collectionToString(Collection<T> collection) { StringBuilder sb = new StringBuilder(); sb.append('{'); boolean isFirstElement = true; for (T element : collection) { if (isFirstElement) { isFirstElement = false; } else { sb.append(','); } sb.append(element); } sb.append('}'); return sb.toString(); } }