001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. 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.apache.logging.log4j.core.helpers;
018
019/**
020 * Utility class providing common validation logic.
021 */
022public final class Assert {
023    private Assert() {
024    }
025
026    /**
027     * Throws a {@code NullPointerException} if the specified parameter is
028     * {@code null}, otherwise returns the specified parameter.
029     * <p>
030     * Usage:
031     *
032     * <pre>
033     * // earlier you would write this:
034     * public SomeConstructor(Object param) {
035     *     if (param == null) {
036     *         throw new NullPointerException(name + &quot; is null&quot;);
037     *     }
038     *     this.field = param;
039     * }
040     *
041     * // now you can do the same in one line:
042     * public SomeConstructor(Object param) {
043     *     this.field = Assert.isNotNull(param);
044     * }
045     * </pre>
046     *
047     * @param <T> the type of the parameter to check and return
048     * @param checkMe the parameter to check
049     * @param name name of the parameter to use in the error message if
050     *            {@code null}
051     * @return the specified parameter
052     */
053    public static <T> T isNotNull(final T checkMe, final String name) {
054        if (checkMe == null) {
055            throw new NullPointerException(name + " is null");
056        }
057        return checkMe;
058    }
059}