public class ListOrderedMap extends AbstractMapDecorator implements OrderedMap, Serializable
Map to ensure that the order of addition is retained
using a List to maintain order.
The order will be used via the iterators and toArray methods on the views.
The order is also returned by the MapIterator.
The orderedMapIterator() method accesses an iterator that can
iterate both forwards and backwards through the map.
In addition, non-interface methods are provided to access the map by index.
If an object is added to the Map for a second time, it will remain in the original position in the iteration.
Note that ListOrderedMap 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.
This class is Serializable from Commons Collections 3.1.
| Modifier and Type | Field and Description |
|---|---|
protected List |
insertOrder
Internal list to hold the sequence of objects
|
map| Modifier | Constructor and Description |
|---|---|
|
ListOrderedMap()
Constructs a new empty
ListOrderedMap that decorates
a HashMap. |
protected |
ListOrderedMap(Map map)
Constructor that wraps (not copies).
|
| Modifier and Type | Method and Description |
|---|---|
List |
asList()
Gets an unmodifiable List view of the keys which changes as the map changes.
|
void |
clear() |
static OrderedMap |
decorate(Map map)
Factory method to create an ordered map.
|
Set |
entrySet()
Gets a view over the entries in the map.
|
Object |
firstKey()
Gets the first key in this map by insert order.
|
Object |
get(int index)
Gets the key at the specified index.
|
Object |
getValue(int index)
Gets the value at the specified index.
|
int |
indexOf(Object key)
Gets the index of the specified key.
|
List |
keyList()
Gets a view over the keys in the map as a List.
|
Set |
keySet()
Gets a view over the keys in the map.
|
Object |
lastKey()
Gets the last key in this map by insert order.
|
MapIterator |
mapIterator()
Obtains a
MapIterator over the map. |
Object |
nextKey(Object key)
Gets the next key to the one specified using insert order.
|
OrderedMapIterator |
orderedMapIterator()
Obtains an
OrderedMapIterator over the map. |
Object |
previousKey(Object key)
Gets the previous key to the one specified using insert order.
|
Object |
put(int index,
Object key,
Object value)
Puts a key-value mapping into the map at the specified index.
|
Object |
put(Object key,
Object value) |
void |
putAll(Map map) |
Object |
remove(int index)
Removes the element at the specified index.
|
Object |
remove(Object key) |
Object |
setValue(int index,
Object value)
Sets the value at the specified index.
|
String |
toString()
Returns the Map as a string.
|
List |
valueList()
Gets a view over the values in the map as a List.
|
Collection |
values()
Gets a view over the values in the map.
|
containsKey, containsValue, equals, get, getMap, hashCode, isEmpty, sizeclone, finalize, getClass, notify, notifyAll, wait, wait, waitcontainsKey, containsValue, equals, get, hashCode, isEmpty, sizeprotected final List insertOrder
public ListOrderedMap()
ListOrderedMap that decorates
a HashMap.protected ListOrderedMap(Map map)
map - the map to decorate, must not be nullIllegalArgumentException - if map is nullpublic static OrderedMap decorate(Map map)
An ArrayList is used to retain order.
map - the map to decorate, must not be nullIllegalArgumentException - if map is nullpublic MapIterator mapIterator()
IterableMapMapIterator over the map.
A map iterator is an efficient way of iterating over maps. There is no need to access the entry set or cast to Map Entry objects.
IterableMap map = new HashedMap();
MapIterator it = map.mapIterator();
while (it.hasNext()) {
Object key = it.next();
Object value = it.getValue();
it.setValue("newValue");
}
mapIterator in interface IterableMappublic OrderedMapIterator orderedMapIterator()
OrderedMapOrderedMapIterator over the map.
A ordered map iterator is an efficient way of iterating over maps in both directions.
BidiMap map = new TreeBidiMap();
MapIterator it = map.mapIterator();
while (it.hasNext()) {
Object key = it.next();
Object value = it.getValue();
it.setValue("newValue");
Object previousKey = it.previous();
}
orderedMapIterator in interface OrderedMappublic Object firstKey()
firstKey in interface OrderedMapNoSuchElementException - if this map is emptypublic Object lastKey()
lastKey in interface OrderedMapNoSuchElementException - if this map is emptypublic Object nextKey(Object key)
nextKey in interface OrderedMapkey - the key to find previous forpublic Object previousKey(Object key)
previousKey in interface OrderedMapkey - the key to find previous forpublic Object put(Object key, Object value)
put in interface Mapput in class AbstractMapDecoratorpublic void putAll(Map map)
putAll in interface MapputAll in class AbstractMapDecoratorpublic Object remove(Object key)
remove in interface Mapremove in class AbstractMapDecoratorpublic void clear()
clear in interface Mapclear in class AbstractMapDecoratorpublic Set keySet()
The Collection will be ordered by object insertion into the map.
keySet in interface MapkeySet in class AbstractMapDecoratorkeyList()public List keyList()
The List will be ordered by object insertion into the map. The List is unmodifiable.
keySet()public Collection values()
The Collection will be ordered by object insertion into the map.
From Commons Collections 3.2, this Collection can be cast
to a list, see valueList()
values in interface Mapvalues in class AbstractMapDecoratorvalueList()public List valueList()
The List will be ordered by object insertion into the map. The List supports remove and set, but does not support add.
values()public Set entrySet()
The Set will be ordered by object insertion into the map.
entrySet in interface MapentrySet in class AbstractMapDecoratorpublic String toString()
toString in class AbstractMapDecoratorpublic Object get(int index)
index - the index to retrieveIndexOutOfBoundsException - if the index is invalidpublic Object getValue(int index)
index - the index to retrieveIndexOutOfBoundsException - if the index is invalidpublic int indexOf(Object key)
key - the key to find the index ofpublic Object setValue(int index, Object value)
index - the index of the value to setIndexOutOfBoundsException - if the index is invalidpublic Object put(int index, Object key, Object value)
If the map already contains the key, then the original mapping is removed and the new mapping added at the specified index. The remove may change the effect of the index. The index is always calculated relative to the original state of the map.
Thus the steps are: (1) remove the existing key-value mapping, then (2) insert the new key-value mapping at the position it would have been inserted had the remove not ocurred.
index - the index at which the mapping should be insertedkey - the keyvalue - the valueIndexOutOfBoundsException - if the index is out of rangepublic Object remove(int index)
index - the index of the object to removenull if none existedIndexOutOfBoundsException - if the index is invalidpublic List asList()
The returned list is unmodifiable because changes to the values of
the list (using 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 the better named
keyList() or keySet().
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