Class DoubleOrderedMap
- All Implemented Interfaces:
Map
This Map is intended for applications that need to be able to look up a key-value pairing by either key or value, and need to do so with equal efficiency.
While that goal could be accomplished by taking a pair of TreeMaps
and redirecting requests to the appropriate TreeMap (e.g.,
containsKey would be directed to the TreeMap that maps values to
keys, containsValue would be directed to the TreeMap that maps keys
to values), there are problems with that implementation,
particularly when trying to keep the two TreeMaps synchronized with
each other. And if the data contained in the TreeMaps is large, the
cost of redundant storage becomes significant. (See also the new
DualTreeBidiMap
and
DualHashBidiMap
implementations.)
This solution keeps the data properly synchronized and minimizes the data storage. The red-black algorithm is based on TreeMap's, but has been modified to simultaneously map a tree node by key and by value. This doubles the cost of put operations (but so does using two TreeMaps), and nearly doubles the cost of remove operations (there is a savings in that the lookup of the node to be removed only has to be performed once). And since only one node contains the key and value, storage is significantly less than that required by two TreeMaps.
There are some limitations placed on data kept in this Map. The biggest one is this:
When performing a put operation, neither the key nor the value may already exist in the Map. In the java.util Map implementations (HashMap, TreeMap), you can perform a put with an already mapped key, and neither cares about duplicate values at all ... but this implementation's put method with throw an IllegalArgumentException if either the key or the value is already in the Map.
Obviously, that same restriction (and consequence of failing to heed that restriction) applies to the putAll method.
The Map.Entry instances returned by the appropriate methods will not allow setValue() and will throw an UnsupportedOperationException on attempts to call that method.
New methods are added to take advantage of the fact that values are kept sorted independently of their keys:
Object getKeyForValue(Object value) is the opposite of get; it takes a value and returns its key, if any.
Object removeValue(Object value) finds and removes the specified value and returns the now un-used key.
Set entrySetByValue() returns the Map.Entry's in a Set whose iterator will iterate over the Map.Entry's in ascending order by their corresponding values.
Set keySetByValue() returns the keys in a Set whose iterator will iterate over the keys in ascending order by their corresponding values.
Collection valuesByValue() returns the values in a Collection whose iterator will iterate over the values in ascending order.
- Since:
- Commons Collections 2.0
- Version:
- $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
- See Also:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprivate class
Deprecated.private static final class
Deprecated.Nested classes/interfaces inherited from class java.util.AbstractMap
AbstractMap.SimpleEntry<K extends Object,
V extends Object>, AbstractMap.SimpleImmutableEntry<K extends Object, V extends Object> -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate Collection[]
Deprecated.private static final String[]
Deprecated.private static final int
Deprecated.private static final int
Deprecated.private int
Deprecated.private int
Deprecated.private static final int
Deprecated.private DoubleOrderedMap.Node[]
Deprecated.private Set[]
Deprecated.private Set[]
Deprecated.private static final int
Deprecated.private static final int
Deprecated. -
Constructor Summary
ConstructorsConstructorDescriptionDeprecated.Construct a new DoubleOrderedMapDoubleOrderedMap
(Map map) Deprecated.Constructs a new DoubleOrderedMap from an existing Map, with keys and values sorted -
Method Summary
Modifier and TypeMethodDescriptionprivate static void
Deprecated.check a key for validity (non-null and implements Comparable)private static void
checkKeyAndValue
(Object key, Object value) Deprecated.check a key and a value for validity (non-null and implements Comparable)private static void
checkNonNullComparable
(Object o, int index) Deprecated.check if an object is fit to be proper input ...private static void
checkValue
(Object value) Deprecated.check a value for validity (non-null and implements Comparable)void
clear()
Deprecated.Removes all mappings from this mapprivate static int
compare
(Comparable o1, Comparable o2) Deprecated.Compare two objectsboolean
containsKey
(Object key) Deprecated.Returns true if this map contains a mapping for the specified key.boolean
containsValue
(Object value) Deprecated.Returns true if this map maps one or more keys to the specified value.private static void
copyColor
(DoubleOrderedMap.Node from, DoubleOrderedMap.Node to, int index) Deprecated.copy the color from one node to another, dealing with the fact that one or both nodes may, in fact, be nullprivate Object
doGet
(Comparable o, int index) Deprecated.common get logic, used to get by key or get by valueprivate void
doRedBlackDelete
(DoubleOrderedMap.Node deletedNode) Deprecated.complicated red-black delete stuff.private void
doRedBlackDeleteFixup
(DoubleOrderedMap.Node replacementNode, int index) Deprecated.complicated red-black delete stuff.private void
doRedBlackInsert
(DoubleOrderedMap.Node insertedNode, int index) Deprecated.complicated red-black insert stuff.private Object
doRemove
(Comparable o, int index) Deprecated.common remove logic (remove by key or remove by value)entrySet()
Deprecated.Returns a set view of the mappings contained in this map.Deprecated.Returns a set view of the mappings contained in this map.Deprecated.Returns the value to which this map maps the specified key.private static DoubleOrderedMap.Node
getGrandParent
(DoubleOrderedMap.Node node, int index) Deprecated.get a node's grandparent.getKeyForValue
(Object value) Deprecated.Returns the key to which this map maps the specified value.private static DoubleOrderedMap.Node
getLeftChild
(DoubleOrderedMap.Node node, int index) Deprecated.get a node's left child.private static DoubleOrderedMap.Node
getParent
(DoubleOrderedMap.Node node, int index) Deprecated.get a node's parent.private static DoubleOrderedMap.Node
getRightChild
(DoubleOrderedMap.Node node, int index) Deprecated.get a node's right child.private void
grow()
Deprecated.bump up the size and note that the map has changedprivate void
insertValue
(DoubleOrderedMap.Node newNode) Deprecated.insert a node by its valueprivate static boolean
isBlack
(DoubleOrderedMap.Node node, int index) Deprecated.is the specified black red? if the node does not exist, sure, it's black, thank youprivate static boolean
isLeftChild
(DoubleOrderedMap.Node node, int index) Deprecated.is this node its parent's left child? mind you, the node, or its parent, may not exist.private static boolean
isRed
(DoubleOrderedMap.Node node, int index) Deprecated.is the specified node red? if the node does not exist, no, it's black, thank youprivate static boolean
isRightChild
(DoubleOrderedMap.Node node, int index) Deprecated.is this node its parent's right child? mind you, the node, or its parent, may not exist.keySet()
Deprecated.Returns a set view of the keys contained in this map.Deprecated.Returns a set view of the keys contained in this map.private static DoubleOrderedMap.Node
leastNode
(DoubleOrderedMap.Node node, int index) Deprecated.find the least node from a given node.private DoubleOrderedMap.Node
lookup
(Comparable data, int index) Deprecated.do the actual lookup of a piece of dataprivate static void
makeBlack
(DoubleOrderedMap.Node node, int index) Deprecated.force a node (if it exists) blackprivate static void
makeRed
(DoubleOrderedMap.Node node, int index) Deprecated.force a node (if it exists) redprivate void
modify()
Deprecated.increment the modification count -- used to check for concurrent modification of the map through the map and through an Iterator from one of its Set or Collection viewsprivate DoubleOrderedMap.Node
nextGreater
(DoubleOrderedMap.Node node, int index) Deprecated.get the next larger node from the specified nodeprivate int
oppositeIndex
(int index) Deprecated.Get the opposite index of the specified indexDeprecated.Associates the specified value with the specified key in this map.Deprecated.Removes the mapping for this key from this map if presentremoveValue
(Object value) Deprecated.Removes the mapping for this value from this map if presentprivate void
rotateLeft
(DoubleOrderedMap.Node node, int index) Deprecated.do a rotate left.private void
rotateRight
(DoubleOrderedMap.Node node, int index) Deprecated.do a rotate right.private void
shrink()
Deprecated.decrement the size and note that the map has changedint
size()
Deprecated.Returns the number of key-value mappings in this map.private void
swapPosition
(DoubleOrderedMap.Node x, DoubleOrderedMap.Node y, int index) Deprecated.swap two nodes (except for their content), taking care of special cases where one is the other's parent ...values()
Deprecated.Returns a collection view of the values contained in this map.Deprecated.Returns a collection view of the values contained in this map.Methods inherited from class java.util.AbstractMap
clone, equals, hashCode, isEmpty, putAll, toString
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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Field Details
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KEY
private static final int KEYDeprecated.- See Also:
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VALUE
private static final int VALUEDeprecated.- See Also:
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SUM_OF_INDICES
private static final int SUM_OF_INDICESDeprecated.- See Also:
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FIRST_INDEX
private static final int FIRST_INDEXDeprecated.- See Also:
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NUMBER_OF_INDICES
private static final int NUMBER_OF_INDICESDeprecated.- See Also:
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dataName
Deprecated. -
rootNode
Deprecated. -
nodeCount
private int nodeCountDeprecated. -
modifications
private int modificationsDeprecated. -
setOfKeys
Deprecated. -
setOfEntries
Deprecated. -
collectionOfValues
Deprecated.
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Constructor Details
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DoubleOrderedMap
public DoubleOrderedMap()Deprecated.Construct a new DoubleOrderedMap -
DoubleOrderedMap
public DoubleOrderedMap(Map map) throws ClassCastException, NullPointerException, IllegalArgumentException Deprecated.Constructs a new DoubleOrderedMap from an existing Map, with keys and values sorted- Parameters:
map
- the map whose mappings are to be placed in this map.- Throws:
ClassCastException
- if the keys in the map are not Comparable, or are not mutually comparable; also if the values in the map are not Comparable, or are not mutually ComparableNullPointerException
- if any key or value in the map is nullIllegalArgumentException
- if there are duplicate keys or duplicate values in the map
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Method Details
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getKeyForValue
Deprecated.Returns the key to which this map maps the specified value. Returns null if the map contains no mapping for this value.- Parameters:
value
- value whose associated key is to be returned.- Returns:
- the key to which this map maps the specified value, or null if the map contains no mapping for this value.
- Throws:
ClassCastException
- if the value is of an inappropriate type for this map.NullPointerException
- if the value is null
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removeValue
Deprecated.Removes the mapping for this value from this map if present- Parameters:
value
- value whose mapping is to be removed from the map.- Returns:
- previous key associated with specified value, or null if there was no mapping for value.
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entrySetByValue
Deprecated.Returns a set view of the mappings contained in this map. Each element in the returned set is a Map.Entry. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.The difference between this method and entrySet is that entrySet's iterator() method returns an iterator that iterates over the mappings in ascending order by key. This method's iterator method iterates over the mappings in ascending order by value.
- Returns:
- a set view of the mappings contained in this map.
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keySetByValue
Deprecated.Returns a set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.The difference between this method and keySet is that keySet's iterator() method returns an iterator that iterates over the keys in ascending order by key. This method's iterator method iterates over the keys in ascending order by value.
- Returns:
- a set view of the keys contained in this map.
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valuesByValue
Deprecated.Returns a collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress, the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.The difference between this method and values is that values's iterator() method returns an iterator that iterates over the values in ascending order by key. This method's iterator method iterates over the values in ascending order by key.
- Returns:
- a collection view of the values contained in this map.
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doRemove
Deprecated.common remove logic (remove by key or remove by value)- Parameters:
o
- the key, or value, that we're looking forindex
- KEY or VALUE- Returns:
- the key, if remove by value, or the value, if remove by key. null if the specified key or value could not be found
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doGet
Deprecated.common get logic, used to get by key or get by value- Parameters:
o
- the key or value that we're looking forindex
- KEY or VALUE- Returns:
- the key (if the value was mapped) or the value (if the key was mapped); null if we couldn't find the specified object
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oppositeIndex
private int oppositeIndex(int index) Deprecated.Get the opposite index of the specified index- Parameters:
index
- KEY or VALUE- Returns:
- VALUE (if KEY was specified), else KEY
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lookup
Deprecated.do the actual lookup of a piece of data- Parameters:
data
- the key or value to be looked upindex
- KEY or VALUE- Returns:
- the desired Node, or null if there is no mapping of the specified data
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compare
Deprecated.Compare two objects- Parameters:
o1
- the first objecto2
- the second object- Returns:
- negative value if o1 < o2; 0 if o1 == o2; positive value if o1 > o2
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leastNode
Deprecated.find the least node from a given node. very useful for starting a sorting iterator ...- Parameters:
node
- the node from which we will start searchingindex
- KEY or VALUE- Returns:
- the smallest node, from the specified node, in the specified mapping
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nextGreater
Deprecated.get the next larger node from the specified node- Parameters:
node
- the node to be searched fromindex
- KEY or VALUE- Returns:
- the specified node
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copyColor
Deprecated.copy the color from one node to another, dealing with the fact that one or both nodes may, in fact, be null- Parameters:
from
- the node whose color we're copying; may be nullto
- the node whose color we're changing; may be nullindex
- KEY or VALUE
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isRed
Deprecated.is the specified node red? if the node does not exist, no, it's black, thank you- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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isBlack
Deprecated.is the specified black red? if the node does not exist, sure, it's black, thank you- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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makeRed
Deprecated.force a node (if it exists) red- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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makeBlack
Deprecated.force a node (if it exists) black- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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getGrandParent
Deprecated.get a node's grandparent. mind you, the node, its parent, or its grandparent may not exist. no problem- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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getParent
Deprecated.get a node's parent. mind you, the node, or its parent, may not exist. no problem- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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getRightChild
Deprecated.get a node's right child. mind you, the node may not exist. no problem- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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getLeftChild
Deprecated.get a node's left child. mind you, the node may not exist. no problem- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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isLeftChild
Deprecated.is this node its parent's left child? mind you, the node, or its parent, may not exist. no problem. if the node doesn't exist ... it's its non-existent parent's left child. If the node does exist but has no parent ... no, we're not the non-existent parent's left child. Otherwise (both the specified node AND its parent exist), check.- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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isRightChild
Deprecated.is this node its parent's right child? mind you, the node, or its parent, may not exist. no problem. if the node doesn't exist ... it's its non-existent parent's right child. If the node does exist but has no parent ... no, we're not the non-existent parent's right child. Otherwise (both the specified node AND its parent exist), check.- Parameters:
node
- the node (may be null) in questionindex
- KEY or VALUE
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rotateLeft
Deprecated.do a rotate left. standard fare in the world of balanced trees- Parameters:
node
- the node to be rotatedindex
- KEY or VALUE
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rotateRight
Deprecated.do a rotate right. standard fare in the world of balanced trees- Parameters:
node
- the node to be rotatedindex
- KEY or VALUE
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doRedBlackInsert
Deprecated.complicated red-black insert stuff. Based on Sun's TreeMap implementation, though it's barely recognizable any more- Parameters:
insertedNode
- the node to be insertedindex
- KEY or VALUE
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doRedBlackDelete
Deprecated.complicated red-black delete stuff. Based on Sun's TreeMap implementation, though it's barely recognizable any more- Parameters:
deletedNode
- the node to be deleted
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doRedBlackDeleteFixup
Deprecated.complicated red-black delete stuff. Based on Sun's TreeMap implementation, though it's barely recognizable any more. This rebalances the tree (somewhat, as red-black trees are not perfectly balanced -- perfect balancing takes longer)- Parameters:
replacementNode
- the node being replacedindex
- KEY or VALUE
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swapPosition
Deprecated.swap two nodes (except for their content), taking care of special cases where one is the other's parent ... hey, it happens.- Parameters:
x
- one nodey
- another nodeindex
- KEY or VALUE
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checkNonNullComparable
Deprecated.check if an object is fit to be proper input ... has to be Comparable and non-null- Parameters:
o
- the object being checkedindex
- KEY or VALUE (used to put the right word in the exception message)- Throws:
NullPointerException
- if o is nullClassCastException
- if o is not Comparable
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checkKey
Deprecated.check a key for validity (non-null and implements Comparable)- Parameters:
key
- the key to be checked- Throws:
NullPointerException
- if key is nullClassCastException
- if key is not Comparable
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checkValue
Deprecated.check a value for validity (non-null and implements Comparable)- Parameters:
value
- the value to be checked- Throws:
NullPointerException
- if value is nullClassCastException
- if value is not Comparable
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checkKeyAndValue
Deprecated.check a key and a value for validity (non-null and implements Comparable)- Parameters:
key
- the key to be checkedvalue
- the value to be checked- Throws:
NullPointerException
- if key or value is nullClassCastException
- if key or value is not Comparable
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modify
private void modify()Deprecated.increment the modification count -- used to check for concurrent modification of the map through the map and through an Iterator from one of its Set or Collection views -
grow
private void grow()Deprecated.bump up the size and note that the map has changed -
shrink
private void shrink()Deprecated.decrement the size and note that the map has changed -
insertValue
Deprecated.insert a node by its value- Parameters:
newNode
- the node to be inserted- Throws:
IllegalArgumentException
- if the node already exists in the value mapping
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size
public int size()Deprecated.Returns the number of key-value mappings in this map. If the map contains more than Integer.MAXVALUE elements, returns Integer.MAXVALUE.- Specified by:
size
in interfaceMap
- Overrides:
size
in classAbstractMap
- Returns:
- the number of key-value mappings in this map.
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containsKey
Deprecated.Returns true if this map contains a mapping for the specified key.- Specified by:
containsKey
in interfaceMap
- Overrides:
containsKey
in classAbstractMap
- Parameters:
key
- key whose presence in this map is to be tested.- Returns:
- true if this map contains a mapping for the specified key.
- Throws:
ClassCastException
- if the key is of an inappropriate type for this map.NullPointerException
- if the key is null
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containsValue
Deprecated.Returns true if this map maps one or more keys to the specified value.- Specified by:
containsValue
in interfaceMap
- Overrides:
containsValue
in classAbstractMap
- Parameters:
value
- value whose presence in this map is to be tested.- Returns:
- true if this map maps one or more keys to the specified value.
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get
Deprecated.Returns the value to which this map maps the specified key. Returns null if the map contains no mapping for this key.- Specified by:
get
in interfaceMap
- Overrides:
get
in classAbstractMap
- Parameters:
key
- key whose associated value is to be returned.- Returns:
- the value to which this map maps the specified key, or null if the map contains no mapping for this key.
- Throws:
ClassCastException
- if the key is of an inappropriate type for this map.NullPointerException
- if the key is null
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put
public Object put(Object key, Object value) throws ClassCastException, NullPointerException, IllegalArgumentException Deprecated.Associates the specified value with the specified key in this map.- Specified by:
put
in interfaceMap
- Overrides:
put
in classAbstractMap
- Parameters:
key
- key with which the specified value is to be associated.value
- value to be associated with the specified key.- Returns:
- null
- Throws:
ClassCastException
- if the class of the specified key or value prevents it from being stored in this map.NullPointerException
- if the specified key or value is nullIllegalArgumentException
- if the key duplicates an existing key, or if the value duplicates an existing value
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remove
Deprecated.Removes the mapping for this key from this map if present- Specified by:
remove
in interfaceMap
- Overrides:
remove
in classAbstractMap
- Parameters:
key
- key whose mapping is to be removed from the map.- Returns:
- previous value associated with specified key, or null if there was no mapping for key.
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clear
public void clear()Deprecated.Removes all mappings from this map- Specified by:
clear
in interfaceMap
- Overrides:
clear
in classAbstractMap
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keySet
Deprecated.Returns a set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.- Specified by:
keySet
in interfaceMap
- Overrides:
keySet
in classAbstractMap
- Returns:
- a set view of the keys contained in this map.
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values
Deprecated.Returns a collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa. If the map is modified while an iteration over the collection is in progress, the results of the iteration are undefined. The collection supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Collection.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations.- Specified by:
values
in interfaceMap
- Overrides:
values
in classAbstractMap
- Returns:
- a collection view of the values contained in this map.
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entrySet
Deprecated.Returns a set view of the mappings contained in this map. Each element in the returned set is a Map.Entry. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress, the results of the iteration are undefined.The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll and clear operations. It does not support the add or addAll operations. The setValue method is not supported on the Map Entry.
- Specified by:
entrySet
in interfaceMap
- Specified by:
entrySet
in classAbstractMap
- Returns:
- a set view of the mappings contained in this map.
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