| /* |
| * 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.commons.collections4.functors; |
| |
| import java.io.Serializable; |
| |
| import org.apache.commons.collections4.Equator; |
| |
| /** |
| * Default {@link Equator} implementation. |
| * |
| * @param <T> the types of object this {@link Equator} can evaluate. |
| * @since 4.0 |
| * @version $Id$ |
| */ |
| public class DefaultEquator<T> implements Equator<T>, Serializable { |
| |
| /** Serial version UID */ |
| private static final long serialVersionUID = 825802648423525485L; |
| |
| /** Static instance */ |
| @SuppressWarnings("rawtypes") // the static instance works for all types |
| public static final DefaultEquator INSTANCE = new DefaultEquator<Object>(); |
| |
| /** |
| * Hashcode used for <code>null</code> objects. |
| */ |
| public static final int HASHCODE_NULL = -1; |
| |
| /** |
| * Factory returning the typed singleton instance. |
| * |
| * @param <T> the object type |
| * @return the singleton instance |
| */ |
| @SuppressWarnings("unchecked") // the static instance works for all types |
| public static <T> DefaultEquator<T> defaultEquator() { |
| return (DefaultEquator<T>) DefaultEquator.INSTANCE; |
| } |
| |
| /** |
| * Restricted constructor. |
| */ |
| private DefaultEquator() { |
| super(); |
| } |
| |
| /** |
| * {@inheritDoc} Delegates to {@link Object#equals(Object)}. |
| */ |
| public boolean equate(final T o1, final T o2) { |
| return o1 == o2 || o1 != null && o1.equals(o2); |
| } |
| |
| /** |
| * {@inheritDoc} |
| * |
| * @return <code>o.hashCode()</code> if <code>o</code> is non- |
| * <code>null</code>, else {@link #HASHCODE_NULL}. |
| */ |
| public int hash(final T o) { |
| return o == null ? HASHCODE_NULL : o.hashCode(); |
| } |
| |
| private Object readResolve() { |
| return INSTANCE; |
| } |
| |
| } |