/*
 * 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
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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 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 Set to ensure it can't be altered.

Attempts to modify it will result in an UnsupportedOperationException.

Type parameters:
  • <K> – the type of the keys in the map
  • <V> – the type of the values in the map
Since:3.0
/** * Decorates a map entry <code>Set</code> to ensure it can't be altered. * <p> * Attempts to modify it will result in an UnsupportedOperationException. * * @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 {
Serialization version
/** Serialization version */
private static final long serialVersionUID = 1678353579659253473L;
Factory method to create an unmodifiable set of Map Entry objects.
Params:
  • set – the set to decorate, must not be null
Type parameters:
  • <K> – the key type
  • <V> – the value type
Throws:
Returns:a new unmodifiable entry set
Since:4.0
/** * 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).
Params:
  • set – the set to decorate, must not be null
Throws:
/** * 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 boolean remove(final Object object) { throw new UnsupportedOperationException(); } @Override public boolean removeAll(final Collection<?> coll) { throw new UnsupportedOperationException(); } @Override public boolean retainAll(final Collection<?> coll) { throw new UnsupportedOperationException(); } //----------------------------------------------------------------------- @Override public Iterator<Map.Entry<K, V>> iterator() { return new UnmodifiableEntrySetIterator(decorated().iterator()); } @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 multi-threaded 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; } //-----------------------------------------------------------------------
Implementation of an entry set iterator.
/** * Implementation of an entry set iterator. */
private 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(); } } //-----------------------------------------------------------------------
Implementation of a map entry that is unmodifiable.
/** * Implementation of a map entry that is unmodifiable. */
private class UnmodifiableEntry extends AbstractMapEntryDecorator<K, V> { protected UnmodifiableEntry(final Map.Entry<K, V> entry) { super(entry); } @Override public V setValue(final V obj) { throw new UnsupportedOperationException(); } } }