org.apache.arrow.memory

Class LowCostIdentityHashMap<K,V extends ValueWithKeyIncluded<K>>

java.lang.Object

org.apache.arrow.memory.LowCostIdentityHashMap<K,V>

Type Parameters:

K - Key type

V - Value type

public class LowCostIdentityHashMap<K,V extends ValueWithKeyIncluded<K>>
extends Object

Highly specialized IdentityHashMap that implements only partial Map APIs. It incurs low initial cost (just two elements by default). It assumes Value includes the Key - Implements @ValueWithKeyIncluded iface that provides "getKey" method.

Constructor Summary

Constructors

Constructor and Description
LowCostIdentityHashMap() Creates a Map with default expected maximum size.
LowCostIdentityHashMap(int maxSize) Creates a Map with the specified maximum size parameter.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all elements from this map, leaving it empty.
boolean	containsKey(K key) Returns whether this map contains the specified key.
boolean	containsValue(V value) Returns whether this map contains the specified value.
V	get(K key) Returns the value of the mapping with the specified key.
V	getNextValue() Special API to return next value - substitute of regular Map.values.iterator().next().
boolean	isEmpty() Returns whether this Map has no elements.
V	put(V value) Maps the specified key to the specified value.
V	remove(K key) Removes the mapping with the specified key from this map.
int	size() Returns the number of mappings in this Map.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

LowCostIdentityHashMap

public LowCostIdentityHashMap()

Creates a Map with default expected maximum size.

LowCostIdentityHashMap

public LowCostIdentityHashMap(int maxSize)

Creates a Map with the specified maximum size parameter.

Parameters:

maxSize - The estimated maximum number of entries that will be put in this map.

Method Detail

clear

public void clear()

Removes all elements from this map, leaving it empty.

See Also:

isEmpty(), size()

containsKey

public boolean containsKey(K key)

Returns whether this map contains the specified key.

Parameters:

key - the key to search for.

Returns:

true if this map contains the specified key, false otherwise.

containsValue

public boolean containsValue(V value)

Returns whether this map contains the specified value.

Parameters:

value - the value to search for.

Returns:

true if this map contains the specified value, false otherwise.

get

public V get(K key)

Returns the value of the mapping with the specified key.

Parameters:

key - the key.

Returns:

the value of the mapping with the specified key.

put

public V put(V value)

Maps the specified key to the specified value.

Parameters:

value - the value.

Returns:

the value of any previous mapping with the specified key or null if there was no such mapping.

remove

public V remove(K key)

Removes the mapping with the specified key from this map.

Parameters:

key - the key of the mapping to remove.

Returns:

the value of the removed mapping, or null if no mapping for the specified key was found.

isEmpty

public boolean isEmpty()

Returns whether this Map has no elements.

Returns:

true if this Map has no elements, false otherwise.

See Also:

size()

size

public int size()

Returns the number of mappings in this Map.

Returns:

the number of mappings in this Map.

getNextValue

public V getNextValue()

Special API to return next value - substitute of regular Map.values.iterator().next().

Returns:

next available value or null if none available