HashMap | +--org.apache.commons.collections.FastHashMap
boolean | Are we currently operating in "fast" mode? |
HashMap | The underlying map we are managing. |
Construct 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(Map map) Construct a new map with the same mappings as the specified map. |
void | clear() Remove all mappings from this map. |
Object | clone() Return a shallow copy of this FastHashMap instance. |
boolean | containsKey(Object key) Return true if this map contains a mapping for the specified key. |
boolean | containsValue(Object value) Return true if this map contains one or more keys mapping to the specified value. |
Set | entrySet() Return a collection view of the mappings contained in this map. |
boolean | equals(Object o) Compare the specified object with this list for equality. |
Object | get(Object key) Return the value to which this map maps the specified key. |
boolean | getFast() Returns true if this map is operating in fast mode. |
int | hashCode() Return the hash code value for this map. |
boolean | isEmpty() Return true if this map contains no mappings. |
Set | keySet() Return a set view of the keys contained in this map. |
Object | put(Object key, Object value) Associate the specified value with the specified key in this map. |
void | putAll(Map in) Copy all of the mappings from the specified map to this one, replacing any mappings with the same keys. |
Object | remove(Object key) Remove any mapping for this key, and return any previously mapped value. |
void | setFast(boolean fast) Sets whether this map is operating in fast mode. |
int | size() Return the number of key-value mappings in this map. |
Collection | values() Return a collection view of the values contained in this map. |
protected boolean fast
protected HashMap map
public FastHashMap()
public FastHashMap(int capacity, float factor)
public FastHashMap(int capacity)
public FastHashMap(Map map)
public void clear()
public Object clone()
FastHashMap
instance.
The keys and values themselves are not copied.
public boolean containsKey(Object key)
true
if this map contains a mapping for the
specified key.
public boolean containsValue(Object value)
true
if this map contains one or more keys mapping
to the specified value.
public Set entrySet()
Map.Entry
.
public boolean equals(Object o)
Map.equals
method.
public Object get(Object key)
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.
public boolean getFast()
public int hashCode()
Map.hashCode
method.
public boolean isEmpty()
true
if this map contains no mappings.
public Set keySet()
public Object put(Object key, Object value)
public void putAll(Map in)
public Object remove(Object key)
public void setFast(boolean fast)
public int size()
public Collection values()
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 callingsetFast(true)
) after initialization is complete. NOTE: If you are creating and accessing aHashMap
only within a single thread, you should usejava.util.HashMap
directly (with no synchronization), for maximum performance. NOTE: This class is not cross-platform. Using it may cause unexpected failures on some architectures. It suffers from the same problems as the double-checked locking idiom. In particular, the instruction that clones the internal collection and the instruction that sets the internal reference to the clone can be executed or perceived out-of-order. This means that any read operation might fail unexpectedly, as it may be reading the state of the internal collection before the internal collection is fully formed. For more information on the double-checked locking idiom, see the Double-Checked Locking Idiom Is Broken Declaration.