Class AbstractHashedMap<K,V>
- java.lang.Object
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- java.util.AbstractMap<K,V>
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- org.apache.commons.collections4.map.AbstractHashedMap<K,V>
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- Type Parameters:
K
- the type of the keys in this mapV
- the type of the values in this map
- All Implemented Interfaces:
Map<K,V>
,Get<K,V>
,IterableGet<K,V>
,IterableMap<K,V>
,Put<K,V>
- Direct Known Subclasses:
AbstractLinkedMap
,AbstractReferenceMap
,CaseInsensitiveMap
,HashedMap
public class AbstractHashedMap<K,V> extends AbstractMap<K,V> implements IterableMap<K,V>
An abstract implementation of a hash-based map which provides numerous points for subclasses to override.This class implements all the features necessary for a subclass hash-based map. Key-value entries are stored in instances of the
HashEntry
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.
NOTE: From Commons Collections 3.1 this class extends AbstractMap. This is to provide backwards compatibility for ReferenceMap between v3.0 and v3.1. This extends clause will be removed in v5.0.
- Since:
- 3.0
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Nested Class Summary
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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>
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues.boolean
containsKey(Object key)
Checks whether the map contains the specified key.boolean
containsValue(Object value)
Checks whether the map contains the specified value.Set<Map.Entry<K,V>>
entrySet()
Gets the entrySet view of the map.boolean
equals(Object obj)
Compares this map with another.V
get(Object key)
Gets the value mapped to the key specified.int
hashCode()
Gets the standard Map hashCode.boolean
isEmpty()
Checks whether the map is currently empty.Set<K>
keySet()
Gets the keySet view of the map.MapIterator<K,V>
mapIterator()
Gets an iterator over the map.V
put(K key, V value)
Puts a key-value mapping into this map.void
putAll(Map<? extends K,? extends V> map)
Puts all the values from the specified map into this map.V
remove(Object key)
Removes the specified mapping from this map.int
size()
Gets the size of the map.String
toString()
Gets the map as a String.Collection<V>
values()
Gets the values view of the map.-
Methods inherited from interface java.util.Map
compute, computeIfAbsent, computeIfPresent, forEach, getOrDefault, merge, putIfAbsent, remove, replace, replace, replaceAll
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Method Detail
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size
public int size()
Gets the size of the map.
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isEmpty
public boolean isEmpty()
Checks whether the map is currently empty.
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containsKey
public boolean containsKey(Object key)
Checks whether the map contains the specified key.- Specified by:
containsKey
in interfaceGet<K,V>
- Specified by:
containsKey
in interfaceMap<K,V>
- Overrides:
containsKey
in classAbstractMap<K,V>
- Parameters:
key
- the key to search for- Returns:
- true if the map contains the key
- See Also:
Map.containsKey(Object)
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containsValue
public boolean containsValue(Object value)
Checks whether the map contains the specified value.- Specified by:
containsValue
in interfaceGet<K,V>
- Specified by:
containsValue
in interfaceMap<K,V>
- Overrides:
containsValue
in classAbstractMap<K,V>
- Parameters:
value
- the value to search for- Returns:
- true if the map contains the value
- See Also:
Map.containsValue(Object)
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putAll
public void putAll(Map<? extends K,? extends V> map)
Puts all the values from the specified map into this map.This implementation iterates around the specified map and uses
put(Object, Object)
.- Specified by:
putAll
in interfaceMap<K,V>
- Specified by:
putAll
in interfacePut<K,V>
- Overrides:
putAll
in classAbstractMap<K,V>
- Parameters:
map
- the map to add- Throws:
NullPointerException
- if the map is null- See Also:
Map.putAll(Map)
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clear
public void clear()
Clears the map, resetting the size to zero and nullifying references to avoid garbage collection issues.
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mapIterator
public MapIterator<K,V> mapIterator()
Gets an iterator over the map. Changes made to the iterator affect this map.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.
- Specified by:
mapIterator
in interfaceIterableGet<K,V>
- Returns:
- the map iterator
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entrySet
public Set<Map.Entry<K,V>> entrySet()
Gets the entrySet view of the map. Changes made to the view affect this map. To simply iterate through the entries, usemapIterator()
.
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keySet
public Set<K> keySet()
Gets the keySet view of the map. Changes made to the view affect this map. To simply iterate through the keys, usemapIterator()
.
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values
public Collection<V> values()
Gets the values view of the map. Changes made to the view affect this map. To simply iterate through the values, usemapIterator()
.
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equals
public boolean equals(Object obj)
Compares this map with another.
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hashCode
public int hashCode()
Gets the standard Map hashCode.
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toString
public String toString()
Gets the map as a String.- Overrides:
toString
in classAbstractMap<K,V>
- Returns:
- a string version of the map
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