Here you can find the source of join(String sep, Object... pieces)
| Parameter | Description |
|---|---|
| sep | the string separator to delimit the different output segments. |
| pieces | A Collection or a varargs Array of objects. |
@SuppressWarnings("unchecked") public static String join(String sep, Object... pieces)
//package com.java2s; /*// w w w . ja va2s . c om * Copyright (C) 2011 The Android Open Source Project * * 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; import java.util.Iterator; public class Main { /** * Turns a sequence of objects into a string, delimited by {@code sep}. If a single * {@code Collection} is passed, it is assumed that the elements of that Collection are to be * joined. Otherwise, wraps the passed {@link Object}(s) in a {@link List} and joins the * generated list. * * @param sep the string separator to delimit the different output segments. * @param pieces A {@link Collection} or a varargs {@code Array} of objects. */ @SuppressWarnings("unchecked") public static String join(String sep, Object... pieces) { if ((pieces.length == 1) && (pieces[0] instanceof Collection)) { // Don't re-wrap the Collection return internalJoin(sep, (Collection<Object>) pieces[0]); } else { return internalJoin(sep, Arrays.asList(pieces)); } } private static String internalJoin(String sep, Collection<Object> pieces) { StringBuilder sb = new StringBuilder(); boolean skipSep = true; Iterator<Object> iter = pieces.iterator(); while (iter.hasNext()) { if (skipSep) { skipSep = false; } else { sb.append(sep); } Object obj = iter.next(); if (obj == null) { sb.append("null"); } else { sb.append(obj.toString()); } } return sb.toString(); } }