Package com.esotericsoftware.kryo.util
Class IdentityMap<K,V>
java.lang.Object
com.esotericsoftware.kryo.util.IdentityMap<K,V>
An unordered map that uses identity comparison for keys. This implementation is a cuckoo hash map using 3 hashes, random
walking, and a small stash for problematic keys. Null keys are not allowed. Null values are allowed. No allocation is done
except when growing the table size.
This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the next higher POT size.
This map performs very fast get, containsKey, and remove (typically O(1), worst case O(log(n))). Put may be a bit slower, depending on hash collisions. Load factors greater than 0.91 greatly increase the chances the map will have to rehash to the next higher POT size.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
static class
static class
static class
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Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionCreates a new map with an initial capacity of 32 and a load factor of 0.8.IdentityMap
(int initialCapacity) Creates a new map with a load factor of 0.8.IdentityMap
(int initialCapacity, float loadFactor) Creates a new map with the specified initial capacity and load factor. -
Method Summary
Modifier and TypeMethodDescriptionvoid
clear()
boolean
containsKey
(K key) boolean
containsValue
(Object value, boolean identity) Returns true if the specified value is in the map.void
ensureCapacity
(int additionalCapacity) Increases the size of the backing array to acommodate the specified number of additional items.entries()
Returns an iterator for the entries in the map.Returns the key for the specified value, or null if it is not in the map.keys()
Returns an iterator for the keys in the map.toString()
values()
Returns an iterator for the values in the map.
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Field Details
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size
public int size
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Constructor Details
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IdentityMap
public IdentityMap()Creates a new map with an initial capacity of 32 and a load factor of 0.8. This map will hold 25 items before growing the backing table. -
IdentityMap
public IdentityMap(int initialCapacity) Creates a new map with a load factor of 0.8. This map will hold initialCapacity * 0.8 items before growing the backing table. -
IdentityMap
public IdentityMap(int initialCapacity, float loadFactor) Creates a new map with the specified initial capacity and load factor. This map will hold initialCapacity * loadFactor items before growing the backing table.
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Method Details
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put
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get
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get
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remove
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clear
public void clear() -
containsValue
Returns true if the specified value is in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.- Parameters:
identity
- If true, uses == to compare the specified value with values in the map. If false, usesObject.equals(Object)
.
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containsKey
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findKey
Returns the key for the specified value, or null if it is not in the map. Note this traverses the entire map and compares every value, which may be an expensive operation.- Parameters:
identity
- If true, uses == to compare the specified value with values in the map. If false, usesObject.equals(Object)
.
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ensureCapacity
public void ensureCapacity(int additionalCapacity) Increases the size of the backing array to acommodate the specified number of additional items. Useful before adding many items to avoid multiple backing array resizes. -
toString
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entries
Returns an iterator for the entries in the map. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use theIdentityMap.Entries
constructor for nested or multithreaded iteration. -
values
Returns an iterator for the values in the map. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use theIdentityMap.Entries
constructor for nested or multithreaded iteration. -
keys
Returns an iterator for the keys in the map. Remove is supported. Note that the same iterator instance is returned each time this method is called. Use theIdentityMap.Entries
constructor for nested or multithreaded iteration.
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