Here you can find the source of toCharArray(Collection
public static char[] toCharArray(Collection<Character> source)
//package com.java2s; /*//ww w .ja v a2 s . c o m * (c) Copyright 2007-2011 by Volker Bergmann. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, is permitted under the terms of the * GNU General Public License. * * For redistributing this software or a derivative work under a license other * than the GPL-compatible Free Software License as defined by the Free * Software Foundation or approved by OSI, you must first obtain a commercial * license to this software product from Volker Bergmann. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * WITHOUT A WARRANTY OF ANY KIND. ALL EXPRESS OR IMPLIED CONDITIONS, * REPRESENTATIONS AND WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE * HEREBY EXCLUDED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ import java.util.*; public class Main { public static char[] toCharArray(Collection<Character> source) { char[] result = new char[source.size()]; int i = 0; for (Character c : source) result[i++] = c; return result; } }