org.apache.commons.collections.map
Class CompositeMap
java.lang.Object
org.apache.commons.collections.map.CompositeMap
- Map
public class CompositeMap
extends java.lang.Object
implements Map
Decorates a map of other maps to provide a single unified view.
Changes made to this map will actually be made on the decorated map.
Add and remove operations require the use of a pluggable strategy. If no
strategy is provided then add and remove are unsupported.
$Revision: 1.7 $ $Date: 2004/02/18 01:13:19 $static interface | CompositeMap.MapMutator - This interface allows definition for all of the indeterminate
mutators in a CompositeMap, as well as providing a hook for
callbacks on key collisions.
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void | addComposited(Map map) - Add an additional Map to the composite.
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void | clear() - Calls
clear() on all composited Maps.
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boolean | containsKey(Object key) - Returns true if this map contains a mapping for the specified
key.
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boolean | containsValue(Object value) - Returns true if this map maps one or more keys to the
specified value.
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Set | entrySet() - Returns a set view of the mappings contained in this map.
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boolean | equals(Object obj) - Checks if this Map equals another as per the Map specification.
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Object | get(Object key) - Returns the value to which this map maps the specified key.
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int | hashCode() - Gets a hash code for the Map as per the Map specification.
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boolean | isEmpty() - Returns true if this map contains no key-value mappings.
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Set | keySet() - Returns a set view of the keys contained in this map.
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Object | put(Object key, Object value) - Associates the specified value with the specified key in this map
(optional operation).
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void | putAll(Map map) - Copies all of the mappings from the specified map to this map
(optional operation).
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Object | remove(Object key) - Removes the mapping for this key from this map if it is present
(optional operation).
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Map | removeComposited(Map map) - Remove a Map from the composite.
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void | setMutator(CompositeMap.MapMutator mutator) - Specify the MapMutator to be used by mutation operations.
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int | size() - Returns the number of key-value mappings in this map.
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Collection | values() - Returns a collection view of the values contained in this map.
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CompositeMap
public CompositeMap()
Create a new, empty, CompositeMap.
CompositeMap
public CompositeMap(Map one,
Map two)
Create a new CompositeMap with two composited Map instances.
one
- the first Map to be compositedtwo
- the second Map to be composited
CompositeMap
public CompositeMap(Map one,
Map two,
CompositeMap.MapMutator mutator)
Create a new CompositeMap with two composited Map instances.
one
- the first Map to be compositedtwo
- the second Map to be compositedmutator
- MapMutator to be used for mutation operations
CompositeMap
public CompositeMap(Map[] composite)
Create a new CompositeMap which composites all of the Map instances in the
argument. It copies the argument array, it does not use it directly.
composite
- the Maps to be composited
CompositeMap
public CompositeMap(Map[] composite,
CompositeMap.MapMutator mutator)
Create a new CompositeMap which composites all of the Map instances in the
argument. It copies the argument array, it does not use it directly.
composite
- Maps to be compositedmutator
- MapMutator to be used for mutation operations
addComposited
public void addComposited(Map map)
throws IllegalArgumentException
Add an additional Map to the composite.
map
- the Map to be added to the composite
clear
public void clear()
Calls clear()
on all composited Maps.
containsKey
public boolean containsKey(Object key)
Returns true if this map contains a mapping for the specified
key. More formally, returns true if and only if
this map contains at a mapping for a key k such that
(key==null ? k==null : key.equals(k)). (There can be
at most one such mapping.)
key
- key whose presence in this map is to be tested.
- true if this map contains a mapping for the specified
key.
containsValue
public boolean containsValue(Object value)
Returns true if this map maps one or more keys to the
specified value. More formally, returns true if and only if
this map contains at least one mapping to a value v such that
(value==null ? v==null : value.equals(v)). This operation
will probably require time linear in the map size for most
implementations of the Map interface.
value
- value whose presence in this map is to be tested.
- true if this map maps one or more keys to the
specified value.
entrySet
public Set entrySet()
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.
This implementation returns a
CompositeSet
which
composites the entry sets from all of the composited maps.
- a set view of the mappings contained in this map.
equals
public boolean equals(Object obj)
Checks if this Map equals another as per the Map specification.
obj
- the object to compare to
- true if the maps are equal
get
public Object get(Object key)
Returns the value to which this map maps the specified key. Returns
null if the map contains no mapping for this key. A return
value of
null does not
necessarily indicate that the
map contains no mapping for the key; it's also possible that the map
explicitly maps the key to
null. The
containsKey
operation may be used to distinguish these two cases.
More formally, if this map contains a mapping from a key
k to a value
v such that
(key==null ? k==null :
key.equals(k)), then this method returns
v; otherwise
it returns
null. (There can be at most one such mapping.)
key
- key whose associated value is to be returned.
- the value to which this map maps the specified key, or
null if the map contains no mapping for this key.
hashCode
public int hashCode()
Gets a hash code for the Map as per the Map specification.
isEmpty
public boolean isEmpty()
Returns true if this map contains no key-value mappings.
- true if this map contains no key-value mappings.
keySet
public Set keySet()
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.
This implementation returns a
CompositeSet
which
composites the key sets from all of the composited maps.
- a set view of the keys contained in this map.
put
public Object put(Object key,
Object value)
Associates the specified value with the specified key in this map
(optional operation). If the map previously contained a mapping for
this key, the old value is replaced by the specified value. (A map
m is said to contain a mapping for a key
k if and only
if
m.containsKey(k)
would return
true.))
key
- key with which the specified value is to be associated.value
- value to be associated with the specified key.
- previous value associated with specified key, or null
if there was no mapping for key. A null return can
also indicate that the map previously associated null
with the specified key, if the implementation supports
null values.
putAll
public void putAll(Map map)
Copies all of the mappings from the specified map to this map
(optional operation). The effect of this call is equivalent to that
of calling
put(k, v)
on this map once
for each mapping from key
k to value
v in the
specified map. The behavior of this operation is unspecified if the
specified map is modified while the operation is in progress.
map
- Mappings to be stored in this map.
remove
public Object remove(Object key)
Removes the mapping for this key from this map if it is present
(optional operation). More formally, if this map contains a mapping
from key
k to value
v such that
(key==null ? k==null : key.equals(k))
, that mapping
is removed. (The map can contain at most one such mapping.)
Returns the value to which the map previously associated the key, or
null if the map contained no mapping for this key. (A
null return can also indicate that the map previously
associated
null with the specified key if the implementation
supports
null values.) The map will not contain a mapping for
the specified key once the call returns.
key
- key whose mapping is to be removed from the map.
- previous value associated with specified key, or null
if there was no mapping for key.
removeComposited
public Map removeComposited(Map map)
Remove a Map from the composite.
map
- the Map to be removed from the composite
- The removed Map or
null
if map is not in the composite
setMutator
public void setMutator(CompositeMap.MapMutator mutator)
Specify the MapMutator to be used by mutation operations.
mutator
- the MapMutator to be used for mutation delegation
size
public int size()
Returns the number of key-value mappings in this map. If the
map contains more than Integer.MAX_VALUE elements, returns
Integer.MAX_VALUE.
- the number of key-value mappings in this map.
values
public Collection values()
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.
- a collection view of the values contained in this map.
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