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/*
 * 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.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.AbstractList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;

import org.apache.commons.collections4.iterators.UnmodifiableIterator;
import org.apache.commons.collections4.iterators.UnmodifiableListIterator;
import org.apache.commons.collections4.list.UnmodifiableList;

/**
 * A Map implementation that maintains the order of the entries.
 * In this implementation order is maintained by original insertion.
 * 

* This implementation improves on the JDK1.4 LinkedHashMap by adding the * {@link org.apache.commons.collections4.MapIterator MapIterator} * functionality, additional convenience methods and allowing * bidirectional iteration. It also implements OrderedMap. * In addition, non-interface methods are provided to access the map by index. *

* The orderedMapIterator() method provides direct access to a * bidirectional iterator. The iterators from the other views can also be cast * to OrderedIterator if required. *

* All the available iterators can be reset back to the start by casting to * ResettableIterator and calling reset(). *

* The implementation is also designed to be subclassed, with lots of useful * methods exposed. *

* Note that LinkedMap is not synchronized and is not thread-safe. * If you wish to use this map from multiple threads concurrently, you must use * appropriate synchronization. The simplest approach is to wrap this map * using {@link java.util.Collections#synchronizedMap(Map)}. This class may throw * exceptions when accessed by concurrent threads without synchronization. * * @since 3.0 * @version $Id: LinkedMap.java 1533984 2013-10-20 21:12:51Z tn $ */ public class LinkedMap extends AbstractLinkedMap implements Serializable, Cloneable { /** Serialisation version */ private static final long serialVersionUID = 9077234323521161066L; /** * Constructs a new empty map with default size and load factor. */ public LinkedMap() { super(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD); } /** * Constructs a new, empty map with the specified initial capacity. * * @param initialCapacity the initial capacity * @throws IllegalArgumentException if the initial capacity is negative */ public LinkedMap(final int initialCapacity) { super(initialCapacity); } /** * Constructs a new, empty map with the specified initial capacity and * load factor. * * @param initialCapacity the initial capacity * @param loadFactor the load factor * @throws IllegalArgumentException if the initial capacity is negative * @throws IllegalArgumentException if the load factor is less than zero */ public LinkedMap(final int initialCapacity, final float loadFactor) { super(initialCapacity, loadFactor); } /** * Constructor copying elements from another map. * * @param map the map to copy * @throws NullPointerException if the map is null */ public LinkedMap(final Map map) { super(map); } //----------------------------------------------------------------------- /** * Clones the map without cloning the keys or values. * * @return a shallow clone */ @Override public LinkedMap clone() { return (LinkedMap) super.clone(); } /** * Write the map out using a custom routine. */ private void writeObject(final ObjectOutputStream out) throws IOException { out.defaultWriteObject(); doWriteObject(out); } /** * Read the map in using a custom routine. */ private void readObject(final ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); doReadObject(in); } //----------------------------------------------------------------------- /** * Gets the key at the specified index. * * @param index the index to retrieve * @return the key at the specified index * @throws IndexOutOfBoundsException if the index is invalid */ public K get(final int index) { return getEntry(index).getKey(); } /** * Gets the value at the specified index. * * @param index the index to retrieve * @return the value at the specified index * @throws IndexOutOfBoundsException if the index is invalid */ public V getValue(final int index) { return getEntry(index).getValue(); } /** * Gets the index of the specified key. * * @param key the key to find the index of * @return the index, or -1 if not found */ public int indexOf(Object key) { key = convertKey(key); int i = 0; for (LinkEntry entry = header.after; entry != header; entry = entry.after, i++) { if (isEqualKey(key, entry.key)) { return i; } } return -1; } /** * Removes the element at the specified index. * * @param index the index of the object to remove * @return the previous value corresponding the key, * or null if none existed * @throws IndexOutOfBoundsException if the index is invalid */ public V remove(final int index) { return remove(get(index)); } /** * Gets an unmodifiable List view of the keys. *

* The returned list is unmodifiable because changes to the values of * the list (using {@link java.util.ListIterator#set(Object)}) will * effectively remove the value from the list and reinsert that value at * the end of the list, which is an unexpected side effect of changing the * value of a list. This occurs because changing the key, changes when the * mapping is added to the map and thus where it appears in the list. *

* An alternative to this method is to use {@link #keySet()}. * * @see #keySet() * @return The ordered list of keys. */ public List asList() { return new LinkedMapList(this); } /** * List view of map. */ static class LinkedMapList extends AbstractList { private final LinkedMap parent; LinkedMapList(final LinkedMap parent) { this.parent = parent; } @Override public int size() { return parent.size(); } @Override public K get(final int index) { return parent.get(index); } @Override public boolean contains(final Object obj) { return parent.containsKey(obj); } @Override public int indexOf(final Object obj) { return parent.indexOf(obj); } @Override public int lastIndexOf(final Object obj) { return parent.indexOf(obj); } @Override public boolean containsAll(final Collection coll) { return parent.keySet().containsAll(coll); } @Override public K remove(final int index) { throw new UnsupportedOperationException(); } @Override public boolean remove(final Object obj) { 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 void clear() { throw new UnsupportedOperationException(); } @Override public Object[] toArray() { return parent.keySet().toArray(); } @Override public T[] toArray(final T[] array) { return parent.keySet().toArray(array); } @Override public Iterator iterator() { return UnmodifiableIterator.unmodifiableIterator(parent.keySet().iterator()); } @Override public ListIterator listIterator() { return UnmodifiableListIterator.umodifiableListIterator(super.listIterator()); } @Override public ListIterator listIterator(final int fromIndex) { return UnmodifiableListIterator.umodifiableListIterator(super.listIterator(fromIndex)); } @Override public List subList(final int fromIndexInclusive, final int toIndexExclusive) { return UnmodifiableList.unmodifiableList(super.subList(fromIndexInclusive, toIndexExclusive)); } } }





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