001/**
002 *
003 * Copyright 2015-2019 Florian Schmaus
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.jivesoftware.smack.util;
018
019import java.util.Collection;
020
021public class Objects {
022
023    /**
024     * Checks that the specified object reference is not <code>null</code> and throws a customized
025     * {@link IllegalArgumentException} if it is.
026     * <p>
027     * Note that unlike <code>java.util.Objects</code>, this method throws an {@link IllegalArgumentException} instead
028     * of an {@link NullPointerException}.
029     * </p>
030     *
031     * @param <T> the type of the reference.
032     * @param obj the object reference to check for nullity.
033     * @param message detail message to be used in the event that a {@link IllegalArgumentException} is thrown.
034     * @return <code>obj</code> if not null.
035     * @throws IllegalArgumentException in case <code>obj</code> is <code>null</code>.
036     */
037    public static <T> T requireNonNull(T obj, String message) throws IllegalArgumentException {
038        if (obj == null) {
039            if (message == null) {
040                message = "Can not provide null argument";
041            }
042            throw new IllegalArgumentException(message);
043        }
044        return obj;
045    }
046
047    public static <T> T requireNonNull(T obj) {
048        return requireNonNull(obj, null);
049    }
050
051    /**
052     * Require a collection to be neither null, nor empty.
053     *
054     * @param collection collection
055     * @param message error message
056     * @param <T> Collection type
057     * @return collection TODO javadoc me please
058     */
059    public static <T extends Collection<?>> T requireNonNullNorEmpty(T collection, String message) {
060        if (requireNonNull(collection).isEmpty()) {
061            throw new IllegalArgumentException(message);
062        }
063        return collection;
064    }
065
066    public static boolean equals(Object a, Object b) {
067        return a == b || (a != null && a.equals(b));
068    }
069}