Class SingletonMap<K,V>
- Type Parameters:
K
- the type of the keys in this mapV
- the type of the values in this map
- All Implemented Interfaces:
Serializable
,Cloneable
,Map<K,
,V> BoundedMap<K,
,V> Get<K,
,V> IterableGet<K,
,V> IterableMap<K,
,V> KeyValue<K,
,V> OrderedMap<K,
,V> Put<K,
V>
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 succeed if the key specified is the same as the singleton key.
The key and value can be obtained by:
- normal Map methods and views
- the
MapIterator
, seemapIterator()
- the
KeyValue
interface (just cast - no object creation)
- Since:
- 3.1
- See Also:
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Nested Class Summary
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Constructor Summary
ConstructorDescriptionConstructor that creates a map ofnull
tonull
.SingletonMap
(Map.Entry<? extends K, ? extends V> mapEntry) Constructor specifying the key and value as aMapEntry
.SingletonMap
(Map<? extends K, ? extends V> map) Constructor copying elements from another map.SingletonMap
(K key, V value) Constructor specifying the key and value.SingletonMap
(KeyValue<K, V> keyValue) Constructor specifying the key and value as aKeyValue
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Method Summary
Modifier and TypeMethodDescriptionvoid
clear()
Unsupported operation.clone()
Clones the map without cloning the key or value.boolean
containsKey
(Object key) Checks whether the map contains the specified key.boolean
containsValue
(Object value) Checks whether the map contains the specified value.entrySet()
Gets the entrySet view of the map.boolean
Compares this map with another.firstKey()
Gets the first (and only) key in the map.Gets the value mapped to the key specified.getKey()
Gets the key.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
(Object key) Compares the specified key to the stored key.protected boolean
isEqualValue
(Object value) Compares the specified value to the stored value.boolean
isFull()
Is the map currently full, always true.keySet()
Gets the unmodifiable keySet view of the map.lastKey()
Gets the last (and only) key in the map.Obtains anOrderedMapIterator
over the map.int
maxSize()
Gets the maximum size of the map, always 1.Gets the next key after the key specified, always null.previousKey
(K key) Gets the previous key before the key specified, always null.Puts a key-value mapping into this map where the key must match the existing key.void
Puts the values from the specified map into this map.Unsupported operation.Sets the value.int
size()
Gets the size of the map, always 1.toString()
Gets the map as a String.values()
Gets the unmodifiable values view of the map.Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.Map
compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll
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Constructor Details
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SingletonMap
public SingletonMap()Constructor that creates a map ofnull
tonull
. -
SingletonMap
Constructor specifying the key and value.- Parameters:
key
- the key to usevalue
- the value to use
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SingletonMap
Constructor specifying the key and value as aKeyValue
.- Parameters:
keyValue
- the key value pair to use
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SingletonMap
Constructor specifying the key and value as aMapEntry
.- Parameters:
mapEntry
- the mapEntry to use
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SingletonMap
Constructor copying elements from another map.- Parameters:
map
- the map to copy, must be size 1- Throws:
NullPointerException
- if the map is nullIllegalArgumentException
- if the size is not 1
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Method Details
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clear
Unsupported operation. -
clone
Clones the map without cloning the key or value. -
containsKey
Checks whether the map contains the specified key.- Specified by:
containsKey
in interfaceGet<K,
V> - Specified by:
containsKey
in interfaceMap<K,
V> - Parameters:
key
- the key to search for- Returns:
- true if the map contains the key
- See Also:
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containsValue
Checks whether the map contains the specified value.- Specified by:
containsValue
in interfaceGet<K,
V> - Specified by:
containsValue
in interfaceMap<K,
V> - Parameters:
value
- the value to search for- Returns:
- true if the map contains the key
- See Also:
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entrySet
Gets the entrySet view of the map. Changes made viasetValue
affect this map. To simply iterate through the entries, usemapIterator()
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equals
Compares this map with another. -
firstKey
Gets the first (and only) key in the map.- Specified by:
firstKey
in interfaceOrderedMap<K,
V> - Returns:
- the key
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get
Gets the value mapped to the key specified. -
getKey
Gets the key. -
getValue
Gets the value. -
hashCode
Gets the standard Map hashCode. -
isEmpty
Checks whether the map is currently empty, which it never is. -
isEqualKey
Compares the specified key to the stored key.- Parameters:
key
- the key to compare- Returns:
- true if equal
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isEqualValue
Compares the specified value to the stored value.- Parameters:
value
- the value to compare- Returns:
- true if equal
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isFull
Is the map currently full, always true.- Specified by:
isFull
in interfaceBoundedMap<K,
V> - Returns:
- true always
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keySet
Gets the unmodifiable keySet view of the map. Changes made to the view affect this map. To simply iterate through the keys, usemapIterator()
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lastKey
Gets the last (and only) key in the map.- Specified by:
lastKey
in interfaceOrderedMap<K,
V> - Returns:
- the key
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mapIterator
Obtains anOrderedMapIterator
over the map.An ordered map iterator is an efficient way of iterating over maps in both directions.
- Specified by:
mapIterator
in interfaceIterableGet<K,
V> - Specified by:
mapIterator
in interfaceOrderedMap<K,
V> - Returns:
- a map iterator
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maxSize
Gets the maximum size of the map, always 1.- Specified by:
maxSize
in interfaceBoundedMap<K,
V> - Returns:
- 1 always
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nextKey
Gets the next key after the key specified, always null.- Specified by:
nextKey
in interfaceOrderedMap<K,
V> - Parameters:
key
- the next key- Returns:
- null always
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previousKey
Gets the previous key before the key specified, always null.- Specified by:
previousKey
in interfaceOrderedMap<K,
V> - Parameters:
key
- the next key- Returns:
- null always
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put
Puts a key-value mapping into this map where the key must match the existing key.An IllegalArgumentException is thrown if the key does not match as the map is fixed size.
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putAll
Puts the values from the specified map into this 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.
- Specified by:
putAll
in interfaceMap<K,
V> - Specified by:
putAll
in interfacePut<K,
V> - Parameters:
map
- the map to add, must be size 0 or 1, and the key must match- Throws:
NullPointerException
- if the map is nullIllegalArgumentException
- if the key does not match- See Also:
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remove
Unsupported operation. -
setValue
Sets the value.- Parameters:
value
- the new value to set- Returns:
- the old value
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size
Gets the size of the map, always 1. -
toString
Gets the map as a String. -
values
Gets the unmodifiable values view of the map. Changes made to the view affect this map. To simply iterate through the values, usemapIterator()
.
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