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java.lang.Objectorg.apache.commons.collections.map.SingletonMap
public class SingletonMap
A Map implementation that holds a single item and is fixed size.
The single key/value pair is specified at creation.
The map is fixed size so any action that would change the size is disallowed.
However, the put or setValue methods can change
the value associated with the key.
If trying to remove or clear the map, an UnsupportedOperationException is thrown. If trying to put a new mapping into the map, an IllegalArgumentException is thrown. The put method will only suceed if the key specified is the same as the singleton key.
The key and value can be obtained by:
MapIterator, see mapIterator()
KeyValue interface (just cast - no object creation)
| Nested Class Summary |
|---|
| Nested classes/interfaces inherited from interface java.util.Map |
|---|
java.util.Map.Entry |
| Constructor Summary | |
|---|---|
SingletonMap()
Constructor that creates a map of null to null. |
|
SingletonMap(KeyValue keyValue)
Constructor specifying the key and value as a KeyValue. |
|
SingletonMap(java.util.Map.Entry mapEntry)
Constructor specifying the key and value as a MapEntry. |
|
SingletonMap(java.util.Map map)
Constructor copying elements from another map. |
|
SingletonMap(java.lang.Object key,
java.lang.Object value)
Constructor specifying the key and value. |
|
| Method Summary | |
|---|---|
void |
clear()
Unsupported operation. |
java.lang.Object |
clone()
Clones the map without cloning the key or value. |
boolean |
containsKey(java.lang.Object key)
Checks whether the map contains the specified key. |
boolean |
containsValue(java.lang.Object value)
Checks whether the map contains the specified value. |
java.util.Set |
entrySet()
Gets the entrySet view of the map. |
boolean |
equals(java.lang.Object obj)
Compares this map with another. |
java.lang.Object |
firstKey()
Gets the first (and only) key in the map. |
java.lang.Object |
get(java.lang.Object key)
Gets the value mapped to the key specified. |
java.lang.Object |
getKey()
Gets the key. |
java.lang.Object |
getValue()
Gets the value. |
int |
hashCode()
Gets the standard Map hashCode. |
boolean |
isEmpty()
Checks whether the map is currently empty, which it never is. |
protected boolean |
isEqualKey(java.lang.Object key)
Compares the specified key to the stored key. |
protected boolean |
isEqualValue(java.lang.Object value)
Compares the specified value to the stored value. |
boolean |
isFull()
Is the map currently full, always true. |
java.util.Set |
keySet()
Gets the unmodifiable keySet view of the map. |
java.lang.Object |
lastKey()
Gets the last (and only) key in the map. |
MapIterator |
mapIterator()
Gets an iterator over the map. |
int |
maxSize()
Gets the maximum size of the map, always 1. |
java.lang.Object |
nextKey(java.lang.Object key)
Gets the next key after the key specified, always null. |
OrderedMapIterator |
orderedMapIterator()
Obtains an OrderedMapIterator over the map. |
java.lang.Object |
previousKey(java.lang.Object key)
Gets the previous key before the key specified, always null. |
java.lang.Object |
put(java.lang.Object key,
java.lang.Object value)
Puts a key-value mapping into this map where the key must match the existing key. |
void |
putAll(java.util.Map map)
Puts the values from the specified map into this map. |
java.lang.Object |
remove(java.lang.Object key)
Unsupported operation. |
java.lang.Object |
setValue(java.lang.Object value)
Sets the value. |
int |
size()
Gets the size of the map, always 1. |
java.lang.String |
toString()
Gets the map as a String. |
java.util.Collection |
values()
Gets the unmodifiable values view of the map. |
| Methods inherited from class java.lang.Object |
|---|
finalize, getClass, notify, notifyAll, wait, wait, wait |
| Constructor Detail |
|---|
public SingletonMap()
null to null.
public SingletonMap(java.lang.Object key,
java.lang.Object value)
key - the key to usevalue - the value to usepublic SingletonMap(KeyValue keyValue)
KeyValue.
keyValue - the key value pair to usepublic SingletonMap(java.util.Map.Entry mapEntry)
MapEntry.
mapEntry - the mapEntry to usepublic SingletonMap(java.util.Map map)
map - the map to copy, must be size 1
java.lang.NullPointerException - if the map is null
java.lang.IllegalArgumentException - if the size is not 1| Method Detail |
|---|
public java.lang.Object getKey()
getKey in interface KeyValuepublic java.lang.Object getValue()
getValue in interface KeyValuepublic java.lang.Object setValue(java.lang.Object value)
value - the new value to set
public boolean isFull()
isFull in interface BoundedMappublic int maxSize()
maxSize in interface BoundedMappublic java.lang.Object get(java.lang.Object key)
get in interface java.util.Mapkey - the key
public int size()
size in interface java.util.Mappublic boolean isEmpty()
isEmpty in interface java.util.Mappublic boolean containsKey(java.lang.Object key)
containsKey in interface java.util.Mapkey - the key to search for
public boolean containsValue(java.lang.Object value)
containsValue in interface java.util.Mapvalue - the value to search for
public java.lang.Object put(java.lang.Object key,
java.lang.Object value)
An IllegalArgumentException is thrown if the key does not match as the map is fixed size.
put in interface java.util.Mapkey - the key to set, must be the key of the mapvalue - the value to set
java.lang.IllegalArgumentException - if the key does not matchpublic void putAll(java.util.Map map)
The map must be of size 0 or size 1. If it is size 1, the key must match the key of this map otherwise an IllegalArgumentException is thrown.
putAll in interface java.util.Mapmap - the map to add, must be size 0 or 1, and the key must match
java.lang.NullPointerException - if the map is null
java.lang.IllegalArgumentException - if the key does not matchpublic java.lang.Object remove(java.lang.Object key)
remove in interface java.util.Mapkey - the mapping to remove
java.lang.UnsupportedOperationException - alwayspublic void clear()
clear in interface java.util.Mappublic java.util.Set entrySet()
setValue affect this map.
To simply iterate through the entries, use mapIterator().
entrySet in interface java.util.Mappublic java.util.Set keySet()
mapIterator().
keySet in interface java.util.Mappublic java.util.Collection values()
mapIterator().
values in interface java.util.Mappublic MapIterator mapIterator()
setValue affect this map.
The remove method is unsupported.
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. It also avoids creating the Map Entry object.
mapIterator in interface IterableMappublic OrderedMapIterator orderedMapIterator()
OrderedMapIterator over the map.
A ordered map iterator is an efficient way of iterating over maps in both directions.
orderedMapIterator in interface OrderedMappublic java.lang.Object firstKey()
firstKey in interface OrderedMappublic java.lang.Object lastKey()
lastKey in interface OrderedMappublic java.lang.Object nextKey(java.lang.Object key)
nextKey in interface OrderedMapkey - the next key
public java.lang.Object previousKey(java.lang.Object key)
previousKey in interface OrderedMapkey - the next key
protected boolean isEqualKey(java.lang.Object key)
key - the key to compare
protected boolean isEqualValue(java.lang.Object value)
value - the value to compare
public java.lang.Object clone()
clone in class java.lang.Objectpublic boolean equals(java.lang.Object obj)
equals in interface java.util.Mapequals in class java.lang.Objectobj - the object to compare to
public int hashCode()
hashCode in interface java.util.MaphashCode in class java.lang.Objectpublic java.lang.String toString()
toString in class java.lang.Object
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