org.apache.commons.collections
クラス FastHashMap

java.lang.Object
  |
  +--java.util.AbstractMap
        |
        +--java.util.HashMap
              |
              +--org.apache.commons.collections.FastHashMap

すべての実装インタフェース:

java.lang.Cloneable, java.util.Map, java.io.Serializable

public class FastHashMap

extends java.util.HashMap

A customized implementation of java.util.HashMap designed to operate in a multithreaded environment where the large majority of method calls are read-only, instead of structural changes. When operating in "fast" mode, read calls are non-synchronized and write calls perform the following steps:

• Clone the existing collection
• Perform the modification on the clone
• Replace the existing collection with the (modified) clone

When first created, objects of this class default to "slow" mode, where all accesses of any type are synchronized but no cloning takes place. This is appropriate for initially populating the collection, followed by a switch to "fast" mode (by calling setFast(true)) after initialization is complete.

NOTE: If you are creating and accessing a HashMap only within a single thread, you should use java.util.HashMap directly (with no synchronization), for maximum performance.

バージョン:

$Revision: 1.4 $ $Date: 2001/05/20 21:03:30 $

作成者:

Craig R. McClanahan

関連項目:

直列化された形式

クラス java.util.Map から継承した内部クラス

java.util.Map.Entry

コンストラクタの概要

FastHashMap()
Construct a an empty map.

FastHashMap(int capacity)
Construct an empty map with the specified capacity.

FastHashMap(int capacity, float factor)
Construct an empty map with the specified capacity and load factor.

FastHashMap(java.util.Map map)
Construct a new map with the same mappings as the specified map.

メソッドの概要

void	clear() Remove all mappings from this map.
java.lang.Object	clone() Return a shallow copy of this FastHashMap instance.
boolean	containsKey(java.lang.Object key) Return true if this map contains a mapping for the specified key.
boolean	containsValue(java.lang.Object value) Return true if this map contains one or more keys mapping to the specified value.
java.util.Set	entrySet() Return a collection view of the mappings contained in this map.
boolean	equals(java.lang.Object o) Compare the specified object with this list for equality.
java.lang.Object	get(java.lang.Object key) Return the value to which this map maps the specified key.
boolean	getFast()
int	hashCode() Return the hash code value for this map.
boolean	isEmpty() Return true if this map contains no mappings.
java.util.Set	keySet() Return a set view of the keys contained in this map.
java.lang.Object	put(java.lang.Object key, java.lang.Object value) Associate the specified value with the specified key in this map.
void	putAll(java.util.Map in) Copy all of the mappings from the specified map to this one, replacing any mappings with the same keys.
java.lang.Object	remove(java.lang.Object key) Remove any mapping for this key, and return any previously mapped value.
void	setFast(boolean fast)
int	size() Return the number of key-value mappings in this map.
java.util.Collection	values() Return a collection view of the values contained in this map.

クラス java.util.AbstractMap から継承したメソッド

toString

クラス java.lang.Object から継承したメソッド

getClass, notify, notifyAll, wait, wait, wait

コンストラクタの詳細

FastHashMap

public FastHashMap()

Construct a an empty map.

FastHashMap

public FastHashMap(int capacity)

Construct an empty map with the specified capacity.

パラメータ:

capacity - The initial capacity of the empty map

FastHashMap

public FastHashMap(int capacity,
                   float factor)

Construct an empty map with the specified capacity and load factor.

パラメータ:

capacity - The initial capacity of the empty map

factor - The load factor of the new map

FastHashMap

public FastHashMap(java.util.Map map)

Construct a new map with the same mappings as the specified map.

パラメータ:

map - The map whose mappings are to be copied

メソッドの詳細

clear

public void clear()

Remove all mappings from this map.

オーバーライド:

クラス java.util.HashMap 内の clear

clone

public java.lang.Object clone()

Return a shallow copy of this FastHashMap instance. The keys and values themselves are not copied.

オーバーライド:

クラス java.util.HashMap 内の clone

containsKey

public boolean containsKey(java.lang.Object key)

Return true if this map contains a mapping for the specified key.

オーバーライド:

クラス java.util.HashMap 内の containsKey

パラメータ:

key - Key to be searched for

containsValue

public boolean containsValue(java.lang.Object value)

Return true if this map contains one or more keys mapping to the specified value.

オーバーライド:

クラス java.util.HashMap 内の containsValue

パラメータ:

value - Value to be searched for

entrySet

public java.util.Set entrySet()

Return a collection view of the mappings contained in this map. Each element in the returned collection is a Map.Entry.

オーバーライド:

クラス java.util.HashMap 内の entrySet

equals

public boolean equals(java.lang.Object o)

Compare the specified object with this list for equality. This implementation uses exactly the code that is used to define the list equals function in the documentation for the Map.equals method.

オーバーライド:

クラス java.util.AbstractMap 内の equals

パラメータ:

o - Object to be compared to this list

get

public java.lang.Object get(java.lang.Object key)

Return the value to which this map maps the specified key. Returns null if the map contains no mapping for this key, or if there is a mapping with a value of null. Use the containsKey() method to disambiguate these cases.

オーバーライド:

クラス java.util.HashMap 内の get

パラメータ:

key - Key whose value is to be returned

getFast

public boolean getFast()

hashCode

public int hashCode()

Return the hash code value for this map. This implementation uses exactly the code that is used to define the list hash function in the documentation for the Map.hashCode method.

オーバーライド:

クラス java.util.AbstractMap 内の hashCode

isEmpty

public boolean isEmpty()

Return true if this map contains no mappings.

オーバーライド:

クラス java.util.HashMap 内の isEmpty

keySet

public java.util.Set keySet()

Return a set view of the keys contained in this map.

オーバーライド:

クラス java.util.HashMap 内の keySet

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)

Associate the specified value with the specified key in this map. If the map previously contained a mapping for this key, the old value is replaced and returned.

オーバーライド:

クラス java.util.HashMap 内の put

パラメータ:

key - The key with which the value is to be associated

value - The value to be associated with this key

putAll

public void putAll(java.util.Map in)

Copy all of the mappings from the specified map to this one, replacing any mappings with the same keys.

オーバーライド:

クラス java.util.HashMap 内の putAll

パラメータ:

in - Map whose mappings are to be copied

remove

public java.lang.Object remove(java.lang.Object key)

Remove any mapping for this key, and return any previously mapped value.

オーバーライド:

クラス java.util.HashMap 内の remove

パラメータ:

key - Key whose mapping is to be removed

setFast

public void setFast(boolean fast)

size

public int size()

Return the number of key-value mappings in this map.

オーバーライド:

クラス java.util.HashMap 内の size

values

public java.util.Collection values()

Return a collection view of the values contained in this map.

オーバーライド:

クラス java.util.HashMap 内の values