001    /****************************************************************
002     * Licensed to the Apache Software Foundation (ASF) under one   *
003     * or more contributor license agreements.  See the NOTICE file *
004     * distributed with this work for additional information        *
005     * regarding copyright ownership.  The ASF licenses this file   *
006     * to you under the Apache License, Version 2.0 (the            *
007     * "License"); you may not use this file except in compliance   *
008     * with the License.  You may obtain a copy of the License at   *
009     *                                                              *
010     *   http://www.apache.org/licenses/LICENSE-2.0                 *
011     *                                                              *
012     * Unless required by applicable law or agreed to in writing,   *
013     * software distributed under the License is distributed on an  *
014     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
015     * KIND, either express or implied.  See the License for the    *
016     * specific language governing permissions and limitations      *
017     * under the License.                                           *
018     ****************************************************************/
019    
020    package org.apache.james.mime4j.util;
021    
022    /**
023     * A set of utility methods to help produce consistent
024     * {@link Object#equals equals} and {@link Object#hashCode hashCode} methods.
025     */
026    public final class LangUtils {
027    
028        public static final int HASH_SEED = 17;
029        public static final int HASH_OFFSET = 37;
030    
031        /** Disabled default constructor. */
032        private LangUtils() {
033        }
034    
035        public static int hashCode(final int seed, final int hashcode) {
036            return seed * HASH_OFFSET + hashcode;
037        }
038    
039        public static int hashCode(final int seed, final boolean b) {
040            return hashCode(seed, b ? 1 : 0);
041        }
042    
043        public static int hashCode(final int seed, final Object obj) {
044            return hashCode(seed, obj != null ? obj.hashCode() : 0);
045        }
046    
047        /**
048         * Check if two objects are equal.
049         *
050         * @param obj1 first object to compare, may be {@code null}
051         * @param obj2 second object to compare, may be {@code null}
052         * @return {@code true} if the objects are equal or both null
053         */
054        public static boolean equals(final Object obj1, final Object obj2) {
055            return obj1 == null ? obj2 == null : obj1.equals(obj2);
056        }
057    
058        /**
059         * Check if two strings are equal, ignoring case considerations.
060         *
061         * @param s1 first string to compare, may be {@code null}
062         * @param s2 second string to compare, may be {@code null}
063         * @return {@code true} if the objects are equal or both null
064         */
065        public static boolean equalsIgnoreCase(final String s1, final String s2) {
066            return s1 == null ? s2 == null : s1.equalsIgnoreCase(s2);
067        }
068    
069    }