- /*
- * Copyright 2003-2004 The Apache Software Foundation
- *
- * Licensed 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.collections.keyvalue;
-
- import java.util.Map;
-
- import org.apache.commons.collections.KeyValue;
-
- /**
- * A mutable KeyValue pair that does not implement MapEntry.
- * <p>
- * Note that a <code>DefaultKeyValue</code> instance may not contain
- * itself as a key or value.
- *
- * @since Commons Collections 3.0
- * @version $Revision: 1.4 $ $Date: 2004/02/18 01:00:08 $
- *
- * @author James Strachan
- * @author Michael A. Smith
- * @author Neil O'Toole
- * @author Stephen Colebourne
- */
- public class DefaultKeyValue extends AbstractKeyValue {
-
- /**
- * Constructs a new pair with a null key and null value.
- */
- public DefaultKeyValue() {
- super(null, null);
- }
-
- /**
- * Constructs a new pair with the specified key and given value.
- *
- * @param key the key for the entry, may be null
- * @param value the value for the entry, may be null
- */
- public DefaultKeyValue(final Object key, final Object value) {
- super(key, value);
- }
-
- /**
- * Constructs a new pair from the specified KeyValue.
- *
- * @param pair the pair to copy, must not be null
- * @throws NullPointerException if the entry is null
- */
- public DefaultKeyValue(final KeyValue pair) {
- super(pair.getKey(), pair.getValue());
- }
-
- /**
- * Constructs a new pair from the specified MapEntry.
- *
- * @param entry the entry to copy, must not be null
- * @throws NullPointerException if the entry is null
- */
- public DefaultKeyValue(final Map.Entry entry) {
- super(entry.getKey(), entry.getValue());
- }
-
- //-----------------------------------------------------------------------
- /**
- * Sets the key.
- *
- * @param key the new key
- * @return the old key
- * @throws IllegalArgumentException if key is this object
- */
- public Object setKey(final Object key) {
- if (key == this) {
- throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a key.");
- }
-
- final Object old = this.key;
- this.key = key;
- return old;
- }
-
- /**
- * Sets the value.
- *
- * @return the old value of the value
- * @param value the new value
- * @throws IllegalArgumentException if value is this object
- */
- public Object setValue(final Object value) {
- if (value == this) {
- throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a value.");
- }
-
- final Object old = this.value;
- this.value = value;
- return old;
- }
-
- //-----------------------------------------------------------------------
- /**
- * Returns a new <code>Map.Entry</code> object with key and value from this pair.
- *
- * @return a MapEntry instance
- */
- public Map.Entry toMapEntry() {
- return new DefaultMapEntry(this);
- }
-
- //-----------------------------------------------------------------------
- /**
- * Compares this Map Entry with another Map Entry.
- * <p>
- * Returns true if the compared object is also a <code>DefaultKeyValue</code>,
- * and its key and value are equal to this object's key and value.
- *
- * @param obj the object to compare to
- * @return true if equal key and value
- */
- public boolean equals(final Object obj) {
- if (obj == this) {
- return true;
- }
- if (obj instanceof DefaultKeyValue == false) {
- return false;
- }
-
- DefaultKeyValue other = (DefaultKeyValue) obj;
- return
- (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey())) &&
- (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue()));
- }
-
- /**
- * Gets a hashCode compatible with the equals method.
- * <p>
- * Implemented per API documentation of {@link java.util.Map.Entry#hashCode()},
- * however subclasses may override this.
- *
- * @return a suitable hash code
- */
- public int hashCode() {
- return (getKey() == null ? 0 : getKey().hashCode()) ^
- (getValue() == null ? 0 : getValue().hashCode());
- }
-
- }