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java.lang.Objectjava.util.AbstractMap
org.apache.commons.collections.map.AbstractHashedMap
org.apache.commons.collections.map.AbstractLinkedMap
public class AbstractLinkedMap
An abstract implementation of a hash-based map that links entries to create an ordered map and which provides numerous points for subclasses to override.
This class implements all the features necessary for a subclass linked
hash-based map. Key-value entries are stored in instances of the
LinkEntry class which can be overridden and replaced.
The iterators can similarly be replaced, without the need to replace the KeySet,
EntrySet and Values view classes.
Overridable methods are provided to change the default hashing behaviour, and to change how entries are added to and removed from the map. Hopefully, all you need for unusual subclasses is here.
This implementation maintains order by original insertion, but subclasses
may work differently. The OrderedMap interface is implemented
to provide access to bidirectional iteration and extra convenience methods.
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.
| Nested Class Summary | |
|---|---|
protected static class |
AbstractLinkedMap.EntrySetIterator
EntrySet iterator. |
protected static class |
AbstractLinkedMap.KeySetIterator
KeySet iterator. |
protected static class |
AbstractLinkedMap.LinkEntry
LinkEntry that stores the data. |
protected static class |
AbstractLinkedMap.LinkIterator
Base Iterator that iterates in link order. |
protected static class |
AbstractLinkedMap.LinkMapIterator
MapIterator implementation. |
protected static class |
AbstractLinkedMap.ValuesIterator
Values iterator. |
| Nested classes/interfaces inherited from class org.apache.commons.collections.map.AbstractHashedMap |
|---|
AbstractHashedMap.EntrySet, AbstractHashedMap.HashEntry, AbstractHashedMap.HashIterator, AbstractHashedMap.HashMapIterator, AbstractHashedMap.KeySet, AbstractHashedMap.Values |
| Nested classes/interfaces inherited from interface java.util.Map |
|---|
java.util.Map.Entry |
| Field Summary | |
|---|---|
protected AbstractLinkedMap.LinkEntry |
header
Header in the linked list |
| Fields inherited from class org.apache.commons.collections.map.AbstractHashedMap |
|---|
data, DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, DEFAULT_THRESHOLD, entrySet, GETKEY_INVALID, GETVALUE_INVALID, keySet, loadFactor, MAXIMUM_CAPACITY, modCount, NO_NEXT_ENTRY, NO_PREVIOUS_ENTRY, NULL, REMOVE_INVALID, SETVALUE_INVALID, size, threshold, values |
| Constructor Summary | |
|---|---|
protected |
AbstractLinkedMap()
Constructor only used in deserialization, do not use otherwise. |
protected |
AbstractLinkedMap(int initialCapacity)
Constructs a new, empty map with the specified initial capacity. |
protected |
AbstractLinkedMap(int initialCapacity,
float loadFactor)
Constructs a new, empty map with the specified initial capacity and load factor. |
protected |
AbstractLinkedMap(int initialCapacity,
float loadFactor,
int threshold)
Constructor which performs no validation on the passed in parameters. |
protected |
AbstractLinkedMap(java.util.Map map)
Constructor copying elements from another map. |
| Method Summary | |
|---|---|
protected 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(java.lang.Object value)
Checks whether the map contains the specified value. |
protected AbstractHashedMap.HashEntry |
createEntry(AbstractHashedMap.HashEntry next,
int hashCode,
java.lang.Object key,
java.lang.Object value)
Creates an entry to store the data. |
protected java.util.Iterator |
createEntrySetIterator()
Creates an entry set iterator. |
protected java.util.Iterator |
createKeySetIterator()
Creates a key set iterator. |
protected java.util.Iterator |
createValuesIterator()
Creates a values iterator. |
protected AbstractLinkedMap.LinkEntry |
entryAfter(AbstractLinkedMap.LinkEntry entry)
Gets the after field from a LinkEntry. |
protected AbstractLinkedMap.LinkEntry |
entryBefore(AbstractLinkedMap.LinkEntry entry)
Gets the before field from a LinkEntry. |
java.lang.Object |
firstKey()
Gets the first key in the map, which is the most recently inserted. |
protected AbstractLinkedMap.LinkEntry |
getEntry(int index)
Gets the key at the specified index. |
protected void |
init()
Initialise this subclass during construction. |
java.lang.Object |
lastKey()
Gets the last key in the map, which is the first inserted. |
MapIterator |
mapIterator()
Gets an iterator over the map. |
java.lang.Object |
nextKey(java.lang.Object key)
Gets the next key in sequence. |
OrderedMapIterator |
orderedMapIterator()
Gets a bidirectional iterator over the map. |
java.lang.Object |
previousKey(java.lang.Object key)
Gets the previous key in sequence. |
protected void |
removeEntry(AbstractHashedMap.HashEntry entry,
int hashIndex,
AbstractHashedMap.HashEntry previous)
Removes an entry from the map and the linked list. |
| Methods inherited from class org.apache.commons.collections.map.AbstractHashedMap |
|---|
addMapping, calculateNewCapacity, calculateThreshold, checkCapacity, clone, containsKey, convertKey, destroyEntry, doReadObject, doWriteObject, ensureCapacity, entryHashCode, entryKey, entryNext, entrySet, entryValue, equals, get, getEntry, hash, hashCode, hashIndex, isEmpty, isEqualKey, isEqualValue, keySet, put, putAll, remove, removeMapping, reuseEntry, size, toString, updateEntry, values |
| Methods inherited from class java.lang.Object |
|---|
finalize, getClass, notify, notifyAll, wait, wait, wait |
| Methods inherited from interface java.util.Map |
|---|
containsKey, entrySet, equals, get, hashCode, isEmpty, keySet, put, putAll, remove, size, values |
| Field Detail |
|---|
protected transient AbstractLinkedMap.LinkEntry header
| Constructor Detail |
|---|
protected AbstractLinkedMap()
protected AbstractLinkedMap(int initialCapacity,
float loadFactor,
int threshold)
initialCapacity - the initial capacity, must be a power of twoloadFactor - the load factor, must be > 0.0f and generally < 1.0fthreshold - the threshold, must be sensibleprotected AbstractLinkedMap(int initialCapacity)
initialCapacity - the initial capacity
java.lang.IllegalArgumentException - if the initial capacity is less than one
protected AbstractLinkedMap(int initialCapacity,
float loadFactor)
initialCapacity - the initial capacityloadFactor - the load factor
java.lang.IllegalArgumentException - if the initial capacity is less than one
java.lang.IllegalArgumentException - if the load factor is less than zeroprotected AbstractLinkedMap(java.util.Map map)
map - the map to copy
java.lang.NullPointerException - if the map is null| Method Detail |
|---|
protected void init()
NOTE: As from v3.2 this method calls
AbstractHashedMap.createEntry(HashEntry, int, Object, Object) to create
the map entry object.
init in class AbstractHashedMappublic boolean containsValue(java.lang.Object value)
containsValue in interface java.util.MapcontainsValue in class AbstractHashedMapvalue - the value to search for
public void clear()
clear in interface java.util.Mapclear in class AbstractHashedMappublic java.lang.Object firstKey()
firstKey in interface OrderedMappublic java.lang.Object lastKey()
lastKey in interface OrderedMappublic java.lang.Object nextKey(java.lang.Object key)
nextKey in interface OrderedMapkey - the key to get after
public java.lang.Object previousKey(java.lang.Object key)
previousKey in interface OrderedMapkey - the key to get before
protected AbstractLinkedMap.LinkEntry getEntry(int index)
index - the index to retrieve
java.lang.IndexOutOfBoundsException - if the index is invalid
protected void addEntry(AbstractHashedMap.HashEntry entry,
int hashIndex)
This implementation adds the entry to the data storage table and to the end of the linked list.
addEntry in class AbstractHashedMapentry - the entry to addhashIndex - the index into the data array to store at
protected AbstractHashedMap.HashEntry createEntry(AbstractHashedMap.HashEntry next,
int hashCode,
java.lang.Object key,
java.lang.Object value)
This implementation creates a new LinkEntry instance.
createEntry in class AbstractHashedMapnext - the next entry in sequencehashCode - the hash code to usekey - the key to storevalue - the value to store
protected void removeEntry(AbstractHashedMap.HashEntry entry,
int hashIndex,
AbstractHashedMap.HashEntry previous)
This implementation removes the entry from the linked list chain, then calls the superclass implementation.
removeEntry in class AbstractHashedMapentry - the entry to removehashIndex - the index into the data structureprevious - the previous entry in the chainprotected AbstractLinkedMap.LinkEntry entryBefore(AbstractLinkedMap.LinkEntry entry)
before field from a LinkEntry.
Used in subclasses that have no visibility of the field.
entry - the entry to query, must not be null
before field of the entry
java.lang.NullPointerException - if the entry is nullprotected AbstractLinkedMap.LinkEntry entryAfter(AbstractLinkedMap.LinkEntry entry)
after field from a LinkEntry.
Used in subclasses that have no visibility of the field.
entry - the entry to query, must not be null
after field of the entry
java.lang.NullPointerException - if the entry is nullpublic MapIterator mapIterator()
A MapIterator returns the keys in the map. It also provides convenient methods to get the key and value, and set the value. It avoids the need to create an entrySet/keySet/values object.
mapIterator in interface IterableMapmapIterator in class AbstractHashedMappublic OrderedMapIterator orderedMapIterator()
A MapIterator returns the keys in the map. It also provides convenient methods to get the key and value, and set the value. It avoids the need to create an entrySet/keySet/values object.
orderedMapIterator in interface OrderedMapprotected java.util.Iterator createEntrySetIterator()
createEntrySetIterator in class AbstractHashedMapprotected java.util.Iterator createKeySetIterator()
createKeySetIterator in class AbstractHashedMapprotected java.util.Iterator createValuesIterator()
createValuesIterator in class AbstractHashedMap
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