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AbstractMap
org.apache.commons.collections.map.AbstractHashedMap
org.apache.commons.collections.map.AbstractLinkedMap
org.apache.commons.collections.map.LinkedMap
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 Collections.synchronizedMap(Map)
. This class may throw
exceptions when accessed by concurrent threads without synchronization.
Nested Class Summary |
Nested classes/interfaces inherited from class org.apache.commons.collections.map.AbstractLinkedMap | |
AbstractLinkedMap.EntrySetIterator , AbstractLinkedMap.KeySetIterator , AbstractLinkedMap.LinkEntry , AbstractLinkedMap.LinkIterator , AbstractLinkedMap.LinkMapIterator , AbstractLinkedMap.ValuesIterator |
Nested classes/interfaces inherited from class org.apache.commons.collections.map.AbstractHashedMap | |
AbstractHashedMap.EntrySet , AbstractHashedMap.EntrySetIterator , AbstractHashedMap.HashEntry , AbstractHashedMap.HashIterator , AbstractHashedMap.HashMapIterator , AbstractHashedMap.KeySet , AbstractHashedMap.KeySetIterator , AbstractHashedMap.Values , AbstractHashedMap.ValuesIterator |
Field Summary |
Fields inherited from class org.apache.commons.collections.map.AbstractLinkedMap | |
header |
Fields inherited from class org.apache.commons.collections.map.AbstractHashedMap | |
DEFAULT_CAPACITY , DEFAULT_LOAD_FACTOR , DEFAULT_THRESHOLD , GETKEY_INVALID , GETVALUE_INVALID , MAXIMUM_CAPACITY , NO_NEXT_ENTRY , NO_PREVIOUS_ENTRY , NULL , REMOVE_INVALID , SETVALUE_INVALID , data , entrySet , keySet , loadFactor , modCount , size , threshold , values |
Constructor Summary | |
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Method Summary | |
List |
|
Object |
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Object |
|
Object |
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int |
|
Object |
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Methods inherited from class org.apache.commons.collections.map.AbstractLinkedMap | |
addEntry , clear , containsValue , createEntry , createEntrySetIterator , createKeySetIterator , createValuesIterator , entryAfter , entryBefore , firstKey , getEntry , init , lastKey , mapIterator , nextKey , orderedMapIterator , previousKey , removeEntry |
Methods inherited from class org.apache.commons.collections.map.AbstractHashedMap | |
addEntry , addMapping , calculateNewCapacity , calculateThreshold , checkCapacity , clear , clone , containsKey , containsValue , convertKey , createEntry , createEntrySetIterator , createKeySetIterator , createValuesIterator , destroyEntry , doReadObject , doWriteObject , ensureCapacity , entryHashCode , entryKey , entryNext , entrySet , entryValue , equals , get , getEntry , hash , hashCode , hashIndex , init , isEmpty , isEqualKey , isEqualValue , keySet , mapIterator , put , putAll , remove , removeEntry , removeMapping , reuseEntry , size , toString , updateEntry , values |
public LinkedMap()
Constructs a new empty map with default size and load factor.
public LinkedMap(Map map)
Constructor copying elements from another map.
- Parameters:
map
- the map to copy
public LinkedMap(int initialCapacity)
Constructs a new, empty map with the specified initial capacity.
- Parameters:
initialCapacity
- the initial capacity
public LinkedMap(int initialCapacity, float loadFactor)
Constructs a new, empty map with the specified initial capacity and load factor.
- Parameters:
initialCapacity
- the initial capacityloadFactor
- the load factor
public List asList()
Gets an unmodifiable List view of the keys. The returned list is unmodifiable because changes to the values of the list (usingListIterator.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 usekeySet()
.
- Returns:
- The ordered list of keys.
- See Also:
keySet()
public Object clone()
Clones the map without cloning the keys or values.
- Overrides:
- clone in interface AbstractHashedMap
- Returns:
- a shallow clone
public Object get(int index)
Gets the key at the specified index.
- Parameters:
index
- the index to retrieve
- Returns:
- the key at the specified index
public Object getValue(int index)
Gets the value at the specified index.
- Parameters:
index
- the index to retrieve
- Returns:
- the key at the specified index
public int indexOf(Object key)
Gets the index of the specified key.
- Parameters:
key
- the key to find the index of
- Returns:
- the index, or -1 if not found
public Object remove(int index)
Removes the element at the specified index.
- Parameters:
index
- the index of the object to remove
- Returns:
- the previous value corresponding the
key
, ornull
if none existed