Java tutorial
//package com.java2s; /* Copyright (C) 2016-2017 Andreas Shimokawa, Carsten Pfeiffer This file is part of Gadgetbridge. Gadgetbridge is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Gadgetbridge is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details. You should have received a copy of the GNU Affero General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ import java.util.Collection; public class Main { /** * Converts a collection of Integer values to an int[] array. * @param values * @return null if the given collection is null, otherwise an array of the same size as the collection * @throws NullPointerException when an element of the collection is null */ public static int[] toIntArray(Collection<Integer> values) { if (values == null) { return null; } int i = 0; int[] result = new int[values.size()]; for (Integer value : values) { result[i++] = value; } return result; } }