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Java example source code file (

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Learn more about this Java project at its project page.

Java - Java tags/keywords

idkey, object, override

The Java example source code

 * 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
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * 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
        public IDKey(final Object _value) {
            // This is the Object hashcode 
            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 hashcode - i.e. the system identity hashcode.
         * @return the hashcode
        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
        public boolean equals(final Object other) {
            if (!(other instanceof IDKey)) {
                return false;
            final IDKey idKey = (IDKey) other;
            if (id != {
                return false;
            // Note that identity equals is used.
            return value == idKey.value;

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