DefaultKeyValue.java
- /*
- * 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.keyvalue;
- import java.util.Map;
- import java.util.Objects;
- import org.apache.commons.collections4.KeyValue;
- /**
- * A mutable {@code KeyValue} pair that does not implement
- * {@link java.util.Map.Entry Map.Entry}.
- * <p>
- * Note that a {@code DefaultKeyValue} instance may not contain
- * itself as a key or value.
- * </p>
- *
- * @param <K> the type of keys
- * @param <V> the type of values
- * @since 3.0
- */
- public class DefaultKeyValue<K, V> extends AbstractKeyValue<K, V> {
- /**
- * 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 K key, final V value) {
- super(key, value);
- }
- /**
- * Constructs a new pair from the specified {@code KeyValue}.
- *
- * @param pair the pair to copy, must not be null
- * @throws NullPointerException if the entry is null
- */
- public DefaultKeyValue(final KeyValue<? extends K, ? extends V> pair) {
- super(pair.getKey(), pair.getValue());
- }
- /**
- * Constructs a new pair from the specified {@code Map.Entry}.
- *
- * @param entry the entry to copy, must not be null
- * @throws NullPointerException if the entry is null
- */
- public DefaultKeyValue(final Map.Entry<? extends K, ? extends V> entry) {
- super(entry.getKey(), entry.getValue());
- }
- /**
- * Compares this {@code Map.Entry} with another {@code Map.Entry}.
- * <p>
- * Returns true if the compared object is also a {@code DefaultKeyValue},
- * 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
- */
- @Override
- public boolean equals(final Object obj) {
- if (obj == this) {
- return true;
- }
- if (!(obj instanceof DefaultKeyValue)) {
- return false;
- }
- final DefaultKeyValue<?, ?> other = (DefaultKeyValue<?, ?>) obj;
- return
- Objects.equals(getKey(), other.getKey()) &&
- Objects.equals(getValue(), 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
- */
- @Override
- public int hashCode() {
- return (getKey() == null ? 0 : getKey().hashCode()) ^
- (getValue() == null ? 0 : getValue().hashCode());
- }
- /**
- * Sets the key.
- *
- * @param key the new key
- * @return the old key
- * @throws IllegalArgumentException if key is this object
- */
- @Override
- public K setKey(final K key) {
- if (key == this) {
- throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a key.");
- }
- return super.setKey(key);
- }
- /**
- * Sets the value.
- *
- * @return the old value of the value
- * @param value the new value
- * @throws IllegalArgumentException if value is this object
- */
- @Override
- public V setValue(final V value) {
- if (value == this) {
- throw new IllegalArgumentException("DefaultKeyValue may not contain itself as a value.");
- }
- return super.setValue(value);
- }
- /**
- * Returns a new {@code Map.Entry} object with key and value from this pair.
- *
- * @return a MapEntry instance
- */
- public Map.Entry<K, V> toMapEntry() {
- return new DefaultMapEntry<>(this);
- }
- }