K - the type of the keys in this mapV - the type of the values in this mappublic class ListOrderedMap<K,V> extends AbstractMapDecorator<K,V> implements OrderedMap<K,V>, 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.
Note that ListOrderedMap doesn't work with
IdentityHashMap, CaseInsensitiveMap,
or similar maps that violate the general contract of Map.
The ListOrderedMap (or, more precisely, the underlying List)
is relying on equals(). This is fine, as long as the
decorated Map is also based on equals(),
and hashCode(), which
IdentityHashMap, and
CaseInsensitiveMap don't: The former uses ==, and
the latter uses equals() on a lower-cased
key.
This class is Serializable starting with Commons Collections 3.1.
| Modifier | Constructor and Description |
|---|---|
|
ListOrderedMap()
Constructs a new empty
ListOrderedMap that decorates
a HashMap. |
protected |
ListOrderedMap(Map<K,V> map)
Constructor that wraps (not copies).
|
| Modifier and Type | Method and Description |
|---|---|
List<K> |
asList()
Gets an unmodifiable List view of the keys which changes as the map changes.
|
void |
clear() |
Set<Map.Entry<K,V>> |
entrySet()
Gets a view over the entries in the map.
|
K |
firstKey()
Gets the first key in this map by insert order.
|
K |
get(int index)
Gets the key at the specified index.
|
V |
getValue(int index)
Gets the value at the specified index.
|
int |
indexOf(Object key)
Gets the index of the specified key.
|
List<K> |
keyList()
Gets a view over the keys in the map as a List.
|
Set<K> |
keySet()
Gets a view over the keys in the map.
|
K |
lastKey()
Gets the last key in this map by insert order.
|
static <K,V> ListOrderedMap<K,V> |
listOrderedMap(Map<K,V> map)
Factory method to create an ordered map.
|
OrderedMapIterator<K,V> |
mapIterator()
Obtains a
MapIterator over the map. |
K |
nextKey(Object key)
Gets the next key to the one specified using insert order.
|
K |
previousKey(Object key)
Gets the previous key to the one specified using insert order.
|
V |
put(int index,
K key,
V value)
Puts a key-value mapping into the map at the specified index.
|
V |
put(K key,
V value)
Note that the return type is Object, rather than V as in the Map interface.
|
void |
putAll(int index,
Map<? extends K,? extends V> map)
Puts the values contained in a supplied Map into the Map starting at
the specified index.
|
void |
putAll(Map<? extends K,? extends V> map) |
V |
remove(int index)
Removes the element at the specified index.
|
V |
remove(Object key) |
V |
setValue(int index,
V value)
Sets the value at the specified index.
|
String |
toString()
Returns the Map as a string.
|
List<V> |
valueList()
Gets a view over the values in the map as a List.
|
Collection<V> |
values()
Gets a view over the values in the map.
|
containsKey, containsValue, decorated, equals, get, hashCode, isEmpty, sizeclone, finalize, getClass, notify, notifyAll, wait, wait, waitcompute, computeIfAbsent, computeIfPresent, containsKey, containsValue, equals, forEach, get, getOrDefault, hashCode, isEmpty, merge, putIfAbsent, remove, replace, replace, replaceAll, sizecontainsKey, containsValue, get, isEmpty, sizepublic ListOrderedMap()
ListOrderedMap that decorates
a HashMap.protected ListOrderedMap(Map<K,V> map)
map - the map to decorate, must not be nullNullPointerException - if map is nullpublic static <K,V> ListOrderedMap<K,V> listOrderedMap(Map<K,V> map)
An ArrayList is used to retain order.
K - the key typeV - the value typemap - the map to decorate, must not be nullNullPointerException - if map is nullpublic OrderedMapIterator<K,V> mapIterator()
AbstractIterableMapMapIterator over the map.
A map iterator is an efficient way of iterating over maps. There is no need to access the entry set or use Map Entry objects.
IterableMap<String,Integer> map = new HashedMap<String,Integer>();
MapIterator<String,Integer> it = map.mapIterator();
while (it.hasNext()) {
String key = it.next();
Integer value = it.getValue();
it.setValue(value + 1);
}
mapIterator in interface IterableGet<K,V>mapIterator in interface OrderedMap<K,V>mapIterator in class AbstractIterableMap<K,V>public K firstKey()
firstKey in interface OrderedMap<K,V>NoSuchElementException - if this map is emptypublic K lastKey()
lastKey in interface OrderedMap<K,V>NoSuchElementException - if this map is emptypublic K nextKey(Object key)
nextKey in interface OrderedMap<K,V>key - the key to find previous forpublic K previousKey(Object key)
previousKey in interface OrderedMap<K,V>key - the key to find previous forpublic V put(K key, V value)
Putput in interface Map<K,V>put in interface Put<K,V>put in class AbstractMapDecorator<K,V>key - key with which the specified value is to be associatedvalue - value to be associated with the specified keykey, or
null if there was no mapping for key.
(A null return can also indicate that the map
previously associated null with key,
if the implementation supports null values.)Map.put(Object, Object)public void putAll(int index, Map<? extends K,? extends V> map)
index - the index in the Map to start at.map - the Map containing the entries to be added.IndexOutOfBoundsException - if the index is out of range [0, size]public V remove(Object key)
remove in interface Map<K,V>remove in interface Get<K,V>remove in class AbstractMapDecorator<K,V>key - key whose mapping is to be removed from the mapkey, or
null if there was no mapping for key.Map.remove(Object)public void clear()
public Set<K> keySet()
The Collection will be ordered by object insertion into the map.
public List<K> keyList()
The List will be ordered by object insertion into the map. The List is unmodifiable.
keySet()public Collection<V> 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()
public List<V> 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<Map.Entry<K,V>> entrySet()
The Set will be ordered by object insertion into the map.
public String toString()
toString in class AbstractMapDecorator<K,V>public K get(int index)
index - the index to retrieveIndexOutOfBoundsException - if the index is invalidpublic V 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 V setValue(int index, V value)
index - the index of the value to setvalue - the new value to setIndexOutOfBoundsException - if the index is invalidpublic V put(int index, K key, V 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 occurred.
index - the index at which the mapping should be insertedkey - the keyvalue - the valueIndexOutOfBoundsException - if the index is out of range [0, size]public V remove(int index)
index - the index of the object to removenull if none existedIndexOutOfBoundsException - if the index is invalidpublic List<K> 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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