org.apache.commons.collections.map
Class LinkedMap
java.lang.Object
|
+--org.apache.commons.collections.map.AbstractHashedMap
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+--org.apache.commons.collections.map.AbstractLinkedMap
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+--org.apache.commons.collections.map.LinkedMap
All Implemented Interfaces:
Cloneable, IterableMap, OrderedMap, Serializable
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
org.apache.commons.collections.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.
- Commons Collections 3.0
- Stephen Colebourne
LinkedMap
public LinkedMap()
Constructs a new empty map with default size and load factor.
LinkedMap
public LinkedMap(int initialCapacity, float loadFactor)
Constructs a new, empty map with the specified initial capacity and
load factor.
- initialCapacity - the initial capacity
- loadFactor - the load factor
- if the initial capacity is less than one
- if the load factor is less than zero
LinkedMap
public LinkedMap(int initialCapacity)
Constructs a new, empty map with the specified initial capacity.
- initialCapacity - the initial capacity
- if the initial capacity is less than one
LinkedMap
public LinkedMap(Map map)
Constructor copying elements from another map.
- map - the map to copy
- if the map is null
asList
public List asList()
Gets an unmodifiable List view of the keys.
The returned list is unmodifiable because changes to the values of
the list (using 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
keySet().
- The ordered list of keys.
keySet()
clone
public Object clone()
Clones the map without cloning the keys or values.
- a shallow clone
get
public Object get(int index)
Gets the key at the specified index.
- index - the index to retrieve
- the key at the specified index
- if the index is invalid
getValue
public Object getValue(int index)
Gets the value at the specified index.
- index - the index to retrieve
- the key at the specified index
- if the index is invalid
indexOf
public int indexOf(Object key)
Gets the index of the specified key.
- key - the key to find the index of
- the index, or -1 if not found
remove
public Object remove(int index)
Removes the element at the specified index.
- index - the index of the object to remove
- the previous value corresponding the key,
or null if none existed
- if the index is invalid
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 org.apache.commons.collections.MapIterator MapIterator functionality, additional convenience methods and allowing bidirectional iteration. It also implementsOrderedMap
. In addition, non-interface methods are provided to access the map by index. TheorderedMapIterator()
method provides direct access to a bidirectional iterator. The iterators from the other views can also be cast toOrderedIterator
if required. All the available iterators can be reset back to the start by casting toResettableIterator
and callingreset()
. The implementation is also designed to be subclassed, with lots of useful methods exposed.