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 * 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.                                           *
 ****************************************************************/

package org.apache.james.mime4j.util;

/**
 * A set of utility methods to help produce consistent
 * {@link Object#equals equals} and {@link Object#hashCode hashCode} methods.
 */
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 strings are equal, ignoring case considerations.
     * 
     * @param s1 first string to compare, may be {@code null}
     * @param s2 second string to compare, may be {@code null}
     * @return {@code true} if the objects are equal or both null
     */
    public static boolean equalsIgnoreCase(final String s1, final String s2) {
        return s1 == null ? s2 == null : s1.equalsIgnoreCase(s2);
    }

}