| /* |
| * 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.lang3.builder; |
| |
| // adapted from org.apache.axis.utils.IDKey |
| |
| /** |
| * Wrap an identity key (System.identityHashCode()) |
| * so that an object can only be equal() to itself. |
| * |
| * This is necessary to disambiguate the occasional duplicate |
| * identityHashCodes that can occur. |
| */ |
| final class IDKey { |
| private final Object value; |
| private final int id; |
| |
| /** |
| * Constructor for IDKey |
| * @param _value The value |
| */ |
| IDKey(final Object _value) { |
| // This is the Object hash code |
| id = System.identityHashCode(_value); |
| // There have been some cases (LANG-459) that return the |
| // same identity hash code for different objects. So |
| // the value is also added to disambiguate these cases. |
| value = _value; |
| } |
| |
| /** |
| * returns hash code - i.e. the system identity hashcode. |
| * @return the hashcode |
| */ |
| @Override |
| public int hashCode() { |
| return id; |
| } |
| |
| /** |
| * checks if instances are equal |
| * @param other The other object to compare to |
| * @return if the instances are for the same object |
| */ |
| @Override |
| public boolean equals(final Object other) { |
| if (!(other instanceof IDKey)) { |
| return false; |
| } |
| final IDKey idKey = (IDKey) other; |
| if (id != idKey.id) { |
| return false; |
| } |
| // Note that identity equals is used. |
| return value == idKey.value; |
| } |
| } |