UnmodifiableEntrySet.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.map;
- import java.lang.reflect.Array;
- import java.util.Collection;
- import java.util.Iterator;
- import java.util.Map;
- import java.util.Set;
- import java.util.function.Predicate;
- import org.apache.commons.collections4.Unmodifiable;
- import org.apache.commons.collections4.iterators.AbstractIteratorDecorator;
- import org.apache.commons.collections4.keyvalue.AbstractMapEntryDecorator;
- import org.apache.commons.collections4.set.AbstractSetDecorator;
- /**
- * Decorates a map entry {@code Set} to ensure it can't be altered.
- * <p>
- * Attempts to modify it will result in an UnsupportedOperationException.
- * </p>
- *
- * @param <K> the type of the keys in the map
- * @param <V> the type of the values in the map
- * @since 3.0
- */
- public final class UnmodifiableEntrySet<K, V>
- extends AbstractSetDecorator<Map.Entry<K, V>> implements Unmodifiable {
- /**
- * Implements a map entry that is unmodifiable.
- */
- private final class UnmodifiableEntry extends AbstractMapEntryDecorator<K, V> {
- protected UnmodifiableEntry(final Map.Entry<K, V> entry) {
- super(entry);
- }
- @Override
- public V setValue(final V value) {
- throw new UnsupportedOperationException();
- }
- }
- /**
- * Implements an entry set iterator.
- */
- private final class UnmodifiableEntrySetIterator extends AbstractIteratorDecorator<Map.Entry<K, V>> {
- protected UnmodifiableEntrySetIterator(final Iterator<Map.Entry<K, V>> iterator) {
- super(iterator);
- }
- @Override
- public Map.Entry<K, V> next() {
- return new UnmodifiableEntry(getIterator().next());
- }
- @Override
- public void remove() {
- throw new UnsupportedOperationException();
- }
- }
- /** Serialization version */
- private static final long serialVersionUID = 1678353579659253473L;
- /**
- * Factory method to create an unmodifiable set of Map Entry objects.
- *
- * @param <K> the key type
- * @param <V> the value type
- * @param set the set to decorate, must not be null
- * @return a new unmodifiable entry set
- * @throws NullPointerException if set is null
- * @since 4.0
- */
- public static <K, V> Set<Map.Entry<K, V>> unmodifiableEntrySet(final Set<Map.Entry<K, V>> set) {
- if (set instanceof Unmodifiable) {
- return set;
- }
- return new UnmodifiableEntrySet<>(set);
- }
- /**
- * Constructor that wraps (not copies).
- *
- * @param set the set to decorate, must not be null
- * @throws NullPointerException if set is null
- */
- private UnmodifiableEntrySet(final Set<Map.Entry<K, V>> set) {
- super(set);
- }
- @Override
- public boolean add(final Map.Entry<K, V> object) {
- throw new UnsupportedOperationException();
- }
- @Override
- public boolean addAll(final Collection<? extends Map.Entry<K, V>> coll) {
- throw new UnsupportedOperationException();
- }
- @Override
- public void clear() {
- throw new UnsupportedOperationException();
- }
- @Override
- public Iterator<Map.Entry<K, V>> iterator() {
- return new UnmodifiableEntrySetIterator(decorated().iterator());
- }
- @Override
- public boolean remove(final Object object) {
- throw new UnsupportedOperationException();
- }
- @Override
- public boolean removeAll(final Collection<?> coll) {
- throw new UnsupportedOperationException();
- }
- /**
- * @since 4.4
- */
- @Override
- public boolean removeIf(final Predicate<? super Map.Entry<K, V>> filter) {
- throw new UnsupportedOperationException();
- }
- @Override
- public boolean retainAll(final Collection<?> coll) {
- throw new UnsupportedOperationException();
- }
- @Override
- @SuppressWarnings("unchecked")
- public Object[] toArray() {
- final Object[] array = decorated().toArray();
- for (int i = 0; i < array.length; i++) {
- array[i] = new UnmodifiableEntry((Map.Entry<K, V>) array[i]);
- }
- return array;
- }
- @Override
- @SuppressWarnings("unchecked")
- public <T> T[] toArray(final T[] array) {
- Object[] result = array;
- if (array.length > 0) {
- // we must create a new array to handle multithreaded situations
- // where another thread could access data before we decorate it
- result = (Object[]) Array.newInstance(array.getClass().getComponentType(), 0);
- }
- result = decorated().toArray(result);
- for (int i = 0; i < result.length; i++) {
- result[i] = new UnmodifiableEntry((Map.Entry<K, V>) result[i]);
- }
- // check to see if result should be returned straight
- if (result.length > array.length) {
- return (T[]) result;
- }
- // copy back into input array to fulfill the method contract
- System.arraycopy(result, 0, array, 0, result.length);
- if (array.length > result.length) {
- array[result.length] = null;
- }
- return array;
- }
- }