public class AbstractLinkedMap extends AbstractHashedMap implements OrderedMap
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.
Modifier and Type | Method and Description |
---|---|
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.
|
java.lang.Object |
firstKey()
Gets the first key in the map, which is the most recently inserted.
|
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.
|
public boolean containsValue(java.lang.Object value)
containsValue
in interface java.util.Map
containsValue
in class AbstractHashedMap
value
- the value to search forpublic void clear()
clear
in interface java.util.Map
clear
in class AbstractHashedMap
public java.lang.Object firstKey()
firstKey
in interface OrderedMap
public java.lang.Object lastKey()
lastKey
in interface OrderedMap
public java.lang.Object nextKey(java.lang.Object key)
nextKey
in interface OrderedMap
key
- the key to get afterpublic java.lang.Object previousKey(java.lang.Object key)
previousKey
in interface OrderedMap
key
- the key to get beforepublic 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 IterableMap
mapIterator
in class AbstractHashedMap
public 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 OrderedMap
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