LinkedMap

Class Overview

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 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 synchronizedMap(Map). This class may throw exceptions when accessed by concurrent threads without synchronization.

Summary

[Expand] Inherited Constants

From class org.apache.commons.collections.map.AbstractHashedMap int DEFAULT_CAPACITY The default capacity to use float DEFAULT_LOAD_FACTOR The default load factor to use int DEFAULT_THRESHOLD The default threshold to use String GETKEY_INVALID String GETVALUE_INVALID int MAXIMUM_CAPACITY The maximum capacity allowed String NO_NEXT_ENTRY String NO_PREVIOUS_ENTRY String REMOVE_INVALID String SETVALUE_INVALID

[Expand] Inherited Fields
From class org.apache.commons.collections.map.AbstractLinkedMap protected AbstractLinkedMap.LinkEntry header Header in the linked list
From class org.apache.commons.collections.map.AbstractHashedMap protected static final Object NULL An object for masking null protected HashEntry[] data Map entries protected AbstractHashedMap.EntrySet entrySet Entry set protected AbstractHashedMap.KeySet keySet Key set protected float loadFactor Load factor, normally 0.75 protected int modCount Modification count for iterators protected int size The size of the map protected int threshold Size at which to rehash protected AbstractHashedMap.Values values Values

[Expand] Inherited Methods
From class org.apache.commons.collections.map.AbstractLinkedMap void addEntry(AbstractHashedMap.HashEntry entry, int hashIndex) Adds an entry into this map, maintaining insertion order. void clear() Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues. boolean containsValue(Object value) Checks whether the map contains the specified value. AbstractHashedMap.HashEntry createEntry(AbstractHashedMap.HashEntry next, int hashCode, Object key, Object value) Creates an entry to store the data. Iterator createEntrySetIterator() Creates an entry set iterator. Iterator createKeySetIterator() Creates a key set iterator. Iterator createValuesIterator() Creates a values iterator. AbstractLinkedMap.LinkEntry entryAfter(AbstractLinkedMap.LinkEntry entry) Gets the after field from a LinkEntry. AbstractLinkedMap.LinkEntry entryBefore(AbstractLinkedMap.LinkEntry entry) Gets the before field from a LinkEntry. Object firstKey() Gets the first key in the map, which is the most recently inserted. AbstractLinkedMap.LinkEntry getEntry(int index) Gets the key at the specified index. void init() Initialise this subclass during construction. Object lastKey() Gets the last key in the map, which is the first inserted. MapIterator mapIterator() Gets an iterator over the map. Object nextKey(Object key) Gets the next key in sequence. OrderedMapIterator orderedMapIterator() Gets a bidirectional iterator over the map. Object previousKey(Object key) Gets the previous key in sequence. void removeEntry(AbstractHashedMap.HashEntry entry, int hashIndex, AbstractHashedMap.HashEntry previous) Removes an entry from the map and the linked list.
From class org.apache.commons.collections.map.AbstractHashedMap void addEntry(AbstractHashedMap.HashEntry entry, int hashIndex) Adds an entry into this map. void addMapping(int hashIndex, int hashCode, Object key, Object value) Adds a new key-value mapping into this map. int calculateNewCapacity(int proposedCapacity) Calculates the new capacity of the map. int calculateThreshold(int newCapacity, float factor) Calculates the new threshold of the map, where it will be resized. void checkCapacity() Checks the capacity of the map and enlarges it if necessary. void clear() Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues. Object clone() Clones the map without cloning the keys or values. boolean containsKey(Object key) Checks whether the map contains the specified key. boolean containsValue(Object value) Checks whether the map contains the specified value. Object convertKey(Object key) Converts input keys to another object for storage in the map. AbstractHashedMap.HashEntry createEntry(AbstractHashedMap.HashEntry next, int hashCode, Object key, Object value) Creates an entry to store the key-value data. Iterator createEntrySetIterator() Creates an entry set iterator. Iterator createKeySetIterator() Creates a key set iterator. Iterator createValuesIterator() Creates a values iterator. void destroyEntry(AbstractHashedMap.HashEntry entry) Kills an entry ready for the garbage collector. void doReadObject(ObjectInputStream in) Reads the map data from the stream. void doWriteObject(ObjectOutputStream out) Writes the map data to the stream. void ensureCapacity(int newCapacity) Changes the size of the data structure to the capacity proposed. int entryHashCode(AbstractHashedMap.HashEntry entry) Gets the hashCode field from a HashEntry. Object entryKey(AbstractHashedMap.HashEntry entry) Gets the key field from a HashEntry. AbstractHashedMap.HashEntry entryNext(AbstractHashedMap.HashEntry entry) Gets the next field from a HashEntry. Set entrySet() Gets the entrySet view of the map. Object entryValue(AbstractHashedMap.HashEntry entry) Gets the value field from a HashEntry. boolean equals(Object obj) Compares this map with another. Object get(Object key) Gets the value mapped to the key specified. AbstractHashedMap.HashEntry getEntry(Object key) Gets the entry mapped to the key specified. int hash(Object key) Gets the hash code for the key specified. int hashCode() Gets the standard Map hashCode. int hashIndex(int hashCode, int dataSize) Gets the index into the data storage for the hashCode specified. void init() Initialise subclasses during construction, cloning or deserialization. boolean isEmpty() Checks whether the map is currently empty. boolean isEqualKey(Object key1, Object key2) Compares two keys, in internal converted form, to see if they are equal. boolean isEqualValue(Object value1, Object value2) Compares two values, in external form, to see if they are equal. Set keySet() Gets the keySet view of the map. MapIterator mapIterator() Gets an iterator over the map. Object put(Object key, Object value) Puts a key-value mapping into this map. void putAll(Map map) Puts all the values from the specified map into this map. Object remove(Object key) Removes the specified mapping from this map. void removeEntry(AbstractHashedMap.HashEntry entry, int hashIndex, AbstractHashedMap.HashEntry previous) Removes an entry from the chain stored in a particular index. void removeMapping(AbstractHashedMap.HashEntry entry, int hashIndex, AbstractHashedMap.HashEntry previous) Removes a mapping from the map. void reuseEntry(AbstractHashedMap.HashEntry entry, int hashIndex, int hashCode, Object key, Object value) Reuses an existing key-value mapping, storing completely new data. int size() Gets the size of the map. String toString() Gets the map as a String. void updateEntry(AbstractHashedMap.HashEntry entry, Object newValue) Updates an existing key-value mapping to change the value. Collection values() Gets the values view of the map.
From class java.util.AbstractMap void clear() Object clone() boolean containsKey(Object arg0) boolean containsValue(Object arg0) abstract Set<Entry<K, V>> entrySet() boolean equals(Object arg0) V get(Object arg0) int hashCode() boolean isEmpty() Set<K> keySet() V put(K arg0, V arg1) void putAll(Map<? extends K, ? extends V> arg0) V remove(Object arg0) int size() String toString() Collection<V> values()
From class java.lang.Object Object clone() boolean equals(Object arg0) void finalize() final Class<?> getClass() int hashCode() final void notify() final void notifyAll() String toString() final void wait() final void wait(long arg0, int arg1) final void wait(long arg0)
From interface java.util.Map abstract void clear() abstract boolean containsKey(Object arg0) abstract boolean containsValue(Object arg0) abstract Set<Entry<K, V>> entrySet() abstract boolean equals(Object arg0) abstract V get(Object arg0) abstract int hashCode() abstract boolean isEmpty() abstract Set<K> keySet() abstract V put(K arg0, V arg1) abstract void putAll(Map<? extends K, ? extends V> arg0) abstract V remove(Object arg0) abstract int size() abstract Collection<V> values()
From interface org.apache.commons.collections.IterableMap abstract MapIterator mapIterator() Obtains a MapIterator over the map.
From interface org.apache.commons.collections.OrderedMap abstract Object firstKey() Gets the first key currently in this map. abstract Object lastKey() Gets the last key currently in this map. abstract Object nextKey(Object key) Gets the next key after the one specified. abstract OrderedMapIterator orderedMapIterator() Obtains an OrderedMapIterator over the map. abstract Object previousKey(Object key) Gets the previous key before the one specified.