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java.lang.Objectgoodsjpi.Persistent
goodslib.PersistentAbstractMap
goodslib.PersistentHashMap
Hash table based implementation of the Map interface. This implementation provides all of the optional map operations, and permits null values and the null key. (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.) This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.
This implementation provides constant-time performance for the basic operations (get and put), assuming the hash function disperses the elements properly among the buckets. Iteration over collection views requires time proportional to the "capacity" of the HashMap instance (the number of buckets) plus its size (the number of key-value mappings). Thus, it's very important not to set the intial capacity too high (or the load factor too low) if iteration performance is important.
Note that this implementation is not synchronized. If multiple threads access this map concurrently, and at least one of the threads modifies the map structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more mappings; merely changing the value associated with a key that an instance already contains is not a structural modification.) This is typically accomplished by synchronizing on some object that naturally encapsulates the map. If no such object exists, the map should be "wrapped" using the Collections.synchronizedMap method. This is best done at creation time, to prevent accidental unsynchronized access to the map:
Map m = Collections.synchronizedMap(new HashMap(...));
The iterators returned by all of this class's "collection view methods" are fail-fast: if the map is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future.
Object.hashCode()
,
Collection
,
Map
,
TreeMap
,
Hashtable
,
Serialized FormField Summary |
Fields inherited from class goodsjpi.Persistent |
defaultMetaobject, metaobject |
Constructor Summary | |
PersistentHashMap()
Constructs a new, empty map with a default capacity and load factor, which is 0.75. |
|
PersistentHashMap(int initialCapacity)
Constructs a new, empty map with the specified initial capacity and default load factor, which is 0.75. |
|
PersistentHashMap(int initialCapacity,
float loadFactor)
Constructs a new, empty map with the specified initial capacity and the specified load factor. |
|
PersistentHashMap(java.util.Map t)
Constructs a new map with the same mappings as the given map. |
Method Summary | |
void |
clear()
Removes all mappings from this map. |
java.lang.Object |
clone()
Returns a shallow copy of this PersistentHashMap instance: the keys and values themselves are not cloned. |
boolean |
containsKey(java.lang.Object key)
Returns true if this map contains a mapping for the specified key. |
boolean |
containsValue(java.lang.Object value)
Returns true if this map maps one or more keys to the specified value. |
java.util.Set |
entrySet()
Returns a collection view of the mappings contained in this map. |
java.lang.Object |
get(java.lang.Object key)
Returns the value to which this map maps the specified key. |
protected goodslib.PersistentHashMap.Entry |
getEntry(java.lang.Object key)
|
goodslib.PersistentHashMap.Entry |
getNext(goodslib.PersistentHashMap.HashIterator iterator)
|
boolean |
isEmpty()
Returns true if this map contains no key-value mappings. |
java.util.Set |
keySet()
Returns a set view of the keys contained in this map. |
java.lang.Object |
put(java.lang.Object key,
java.lang.Object value)
Associates the specified value with the specified key in this map. |
void |
putAll(java.util.Map t)
Copies all of the mappings from the specified map to this one. |
java.lang.Object |
remove(java.lang.Object key)
Removes the mapping for this key from this map if present. |
void |
removeCurr(goodslib.PersistentHashMap.HashIterator iterator)
|
int |
size()
Returns the number of key-value mappings in this map. |
java.util.Collection |
values()
Returns a collection view of the values contained in this map. |
Methods inherited from class goodslib.PersistentAbstractMap |
equals, hashCode, toString |
Methods inherited from class goodsjpi.Persistent |
attachToStorage, clusterWith, finalize, getDatabase, getOid, getStorageId, onLoad |
Methods inherited from class java.lang.Object |
getClass, notify, notifyAll, wait, wait, wait |
Methods inherited from interface java.util.Map |
equals, hashCode |
Constructor Detail |
public PersistentHashMap(int initialCapacity, float loadFactor)
initialCapacity
- the initial capacity of the PersistentHashMap.loadFactor
- the load factor of the PersistentHashMap
java.lang.IllegalArgumentException
- if the initial capacity is less
than zero, or if the load factor is nonpositive.public PersistentHashMap(int initialCapacity)
initialCapacity
- the initial capacity of the PersistentHashMap.
java.lang.IllegalArgumentException
- if the initial capacity is less
than zero.public PersistentHashMap()
public PersistentHashMap(java.util.Map t)
t
- the map whose mappings are to be placed in this map.Method Detail |
public int size()
size
in interface java.util.Map
size
in class PersistentAbstractMap
public boolean isEmpty()
isEmpty
in interface java.util.Map
isEmpty
in class PersistentAbstractMap
public boolean containsValue(java.lang.Object value)
containsValue
in interface java.util.Map
containsValue
in class PersistentAbstractMap
value
- value whose presence in this map is to be tested.
public boolean containsKey(java.lang.Object key)
containsKey
in interface java.util.Map
containsKey
in class PersistentAbstractMap
key
- key whose presence in this Map is to be tested.
protected goodslib.PersistentHashMap.Entry getEntry(java.lang.Object key)
public java.lang.Object get(java.lang.Object key)
get
in interface java.util.Map
get
in class PersistentAbstractMap
key
- key whose associated value is to be returned.
PersistentAbstractMap.containsKey(Object)
public java.lang.Object put(java.lang.Object key, java.lang.Object value)
put
in interface java.util.Map
put
in class PersistentAbstractMap
key
- key with which the specified value is to be associated.value
- value to be associated with the specified key.
public java.lang.Object remove(java.lang.Object key)
remove
in interface java.util.Map
remove
in class PersistentAbstractMap
key
- key whose mapping is to be removed from the map.
public void putAll(java.util.Map t)
putAll
in interface java.util.Map
putAll
in class PersistentAbstractMap
t
- Mappings to be stored in this map.public void clear()
clear
in interface java.util.Map
clear
in class PersistentAbstractMap
public java.lang.Object clone()
clone
in class Persistent
public goodslib.PersistentHashMap.Entry getNext(goodslib.PersistentHashMap.HashIterator iterator)
public void removeCurr(goodslib.PersistentHashMap.HashIterator iterator)
public java.util.Set keySet()
keySet
in interface java.util.Map
keySet
in class PersistentAbstractMap
public java.util.Collection values()
values
in interface java.util.Map
values
in class PersistentAbstractMap
public java.util.Set entrySet()
entrySet
in interface java.util.Map
entrySet
in class PersistentAbstractMap
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