httpcore5/src/main/java/org/apache/hc/core5/util/LangUtils.java

/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.hc.core5.util;

/**
 * A set of utility methods to help produce consistent
 * {@link Object#equals equals} and {@link Object#hashCode hashCode} methods.
 *
 *
 * @since 4.0
 */
public final class LangUtils {

    public static final int HASH_SEED = 17;
    public static final int HASH_OFFSET = 37;

    /** Disabled default constructor. */
    private LangUtils() {
    }

    public static int hashCode(final int seed, final int hashcode) {
        return seed * HASH_OFFSET + hashcode;
    }

    public static int hashCode(final int seed, final boolean b) {
        return hashCode(seed, b ? 1 : 0);
    }

    public static int hashCode(final int seed, final Object obj) {
        return hashCode(seed, obj != null ? obj.hashCode() : 0);
    }

    /**
     * Check if two objects are equal.
     *
     * @param obj1 first object to compare, may be {@code null}
     * @param obj2 second object to compare, may be {@code null}
     * @return {@code true} if the objects are equal or both null
     */
    public static boolean equals(final Object obj1, final Object obj2) {
        return obj1 == null ? obj2 == null : obj1.equals(obj2);
    }

    /**
     * Check if two object arrays are equal.
     * <ul>
     * <li>If both parameters are null, return {@code true}</li>
     * <li>If one parameter is null, return {@code false}</li>
     * <li>If the array lengths are different, return {@code false}</li>
     * <li>Compare array elements using .equals(); return {@code false} if any comparisons fail.</li>
     * <li>Return {@code true}</li>
     * </ul>
     *
     * @param a1 first array to compare, may be {@code null}
     * @param a2 second array to compare, may be {@code null}
     * @return {@code true} if the arrays are equal or both null
     */
    public static boolean equals(final Object[] a1, final Object[] a2) {
        if (a1 == null) {
            return a2 == null;
        }
        if (a2 != null && a1.length == a2.length) {
            for (int i = 0; i < a1.length; i++) {
                if (!equals(a1[i], a2[i])) {
                    return false;
                }
            }
            return true;
        }
        return false;
    }

}