Package com.esotericsoftware.kryo.util
Class IdentityMap<K,V>
- java.lang.Object
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- com.esotericsoftware.kryo.util.IdentityMap<K,V>
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public class IdentityMap<K,V> extends java.lang.Object
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.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
IdentityMap.Entries<K,V>
static class
IdentityMap.Entry<K,V>
static class
IdentityMap.Keys<K>
static class
IdentityMap.Values<V>
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Field Summary
Fields Modifier and Type Field Description int
size
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Constructor Summary
Constructors Constructor Description IdentityMap()
Creates 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.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
clear()
boolean
containsKey(K key)
boolean
containsValue(java.lang.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.IdentityMap.Entries<K,V>
entries()
Returns an iterator for the entries in the map.K
findKey(java.lang.Object value, boolean identity)
Returns the key for the specified value, or null if it is not in the map.V
get(K key)
V
get(K key, V defaultValue)
IdentityMap.Keys<K>
keys()
Returns an iterator for the keys in the map.V
put(K key, V value)
V
remove(K key)
java.lang.String
toString()
IdentityMap.Values<V>
values()
Returns an iterator for the values in the map.
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Constructor Detail
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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.
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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.
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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 Detail
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clear
public void clear()
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containsValue
public boolean containsValue(java.lang.Object value, boolean identity)
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
public boolean containsKey(K key)
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findKey
public K findKey(java.lang.Object value, boolean identity)
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.
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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entries
public IdentityMap.Entries<K,V> 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.
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values
public IdentityMap.Values<V> 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.
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keys
public IdentityMap.Keys<K> 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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