Class COM.odi.util.OSHashBag

java.lang.Object
   |
   +----COM.odi.util.OSHashBag

public class OSHashBag
extends Object
implements IPersistent, Cloneable, Collection, FastContains, Serializable

OSHashBag implements a persistent collection, possibly containing duplicates. OSHashBag implements the API specified by the java.util.Collection interface. The equals() and hashCode() methods are reference-based, not content-based (they differ in this way from the equals() and hashCode() methods specified by java.util.Set and java.util.List). Certain operations on OSHashBag that require comparison of objects might cause ObjectStore to throw ReferencedObjectNotFoundException. If this occurs, it indicates that one or more of the values referenced by the underlying hash table cannot be accessed, most likely because they have been destroyed. The OSHashBag class provides a clearDestroyed() operation that can be used to remove entries that contain these references to these destroyed objects.

Additional information about OSHashBag is in the user guide. Here are exceptions that might be thrown by many of the methods in this class:

DatabaseNotOpenException If the database containing the object is not open.

NoTransactionInProgressException If there is no transaction in progress.

ObjectNotFoundException If the object was not found, either because the object itself, its segment, or its database was destroyed.

ObjectException Ifthe object was local and was fetched in a previous transaction.

ObjectStoreException If the session implied by an argument to the call or the object the method is called on is not the same as the session associated with the current thread.

UpdateReadOnlyException If there is a readonly transaction in progress or if the database is open for readonly.

See Also:: IPersistent, Collection

OSHashBag(): Create a new, empty OSHashBag.
OSHashBag(int): Create a new, empty OSHashBag, and allocate a backing hashtable of the specified size.

add(Object): Ensures that this Collection contains the specified element.
addAll(Collection): Adds all of the elements in the specified Collection to this Collection, if they were not already present.
clear(): Removes all of the elements from this Collection.
clearDestroyed(): Removes from the hash table all entries which reference destroyed objects either as a key or value.
contains(Object): Returns true if this Collection contains the specified element.
containsAll(Collection): Returns true if this Collection contains all of the elements in the specified Collection.
duplicateCount(Object): Returns the duplicate count for the specified element, or 0 if the element is not contained in the bag.
hashCode(): Returns the hash code for the object.
isEmpty(): Returns true if this Collection contains no elements.
iterator(): Returns an Iterator over the elements in this Collection.
remove(Object): Removes a single instance of the specified element from this Collection, if it is present.
removeAll(Collection): Removes from this collection all of its elements that are contained in the specified collection.
retainAll(Collection): Retains only the elements in this collection that are contained in the specified collection.
size(): Returns the number of elements in this Collection.
toArray(): Returns an array containing all of the elements in this Collection.

OSHashBag

  public OSHashBag()

Create a new, empty OSHashBag.

OSHashBag

  public OSHashBag(int initSize)

Create a new, empty OSHashBag, and allocate a backing hashtable of the specified size.

clearDestroyed

  public void clearDestroyed()

Removes from the hash table all entries which reference destroyed objects either as a key or value. The current implementation of this method requires that all key, value objects referenced by the OSHashtable be fetched, which may require significant heap space.

duplicateCount

  public int duplicateCount(Object o)

Returns the duplicate count for the specified element, or 0 if the element is not contained in the bag.

Parameters:: o - element whose presence in this Collection is to be tested.

size

  public int size()

Returns the number of elements in this Collection.

isEmpty

  public boolean isEmpty()

Returns true if this Collection contains no elements.

contains

  public boolean contains(Object o)

Returns true if this Collection contains the specified element. More formally, returns true if and only if this Collection contains at least one element e such that o.equals(e).

Parameters:: o - element whose presence in this Collection is to be tested.

iterator

  public Iterator iterator()

Returns an Iterator over the elements in this Collection. There are no guarantees concerning the order in which the elements are returned.

toArray

  public Object[] toArray()

Returns an array containing all of the elements in this Collection. The returned array will be "safe" in that no references to it are maintained by the Collection. (In other words, this method must allocate a new array even if the Collection is backed by an Array). The caller is thus free to modify the returned array.

This method acts as bridge between array-based and Collection-based APIs.

add

  public boolean add(Object o)

Ensures that this Collection contains the specified element. Returns true if the Collection changed as a result of the call. Returns false if this Collection does not permit duplicates and already contains the specified element.

Parameters:: o - element whose presence in this Collection is to be ensured.
Returns:: true if the Collection changed as a result of the call.

remove

  public boolean remove(Object o)

Removes a single instance of the specified element from this Collection, if it is present. More formally, removes an element e such that o.equals(e), if the Collection contains one or more such elements. Returns true if the Collection contained the specified element (or equivalently, if the Collection changed as a result of the call).

Parameters:: o - element to be removed from this Collection, if present.
Returns:: true if the Collection changed as a result of the call.

containsAll

  public boolean containsAll(Collection c)

Returns true if this Collection contains all of the elements in the specified Collection. Both this collection and the specified collection are treated as sets for the purposes of this operation (that is, duplicate elements are ignored).

See Also:: contains

addAll

  public boolean addAll(Collection c)

Adds all of the elements in the specified Collection to this Collection, if they were not already present. Both this collection and the specified collection are treated as sets for the purposes of this operations (that is, duplicate elements are ignored). The behavior of this operation is undefined if the specified Collection is modified while the operation is in progress. (This implies that the behavior of this call is undefined if the the specified Collection is this Collection, and this Collection is nonempty.)

Parameters:: c - elements to be inserted into this Collection.
Returns:: true if this Collection changed as a result of the call.
See Also:: add

removeAll

  public boolean removeAll(Collection c)

Removes from this collection all of its elements that are contained in the specified collection. Both this collection and the specified collection are treated as sets for the purposes of this operation (that is, duplicate elements are ignored). After this call returns, this collection will contains no elements in common with the specified collection, even if this collection may have had duplicate elements.

Parameters:: c - elements to be removed from this Collection.
Returns:: true if this Collection changed as a result of the call.
See Also:: remove, contains

retainAll

  public boolean retainAll(Collection coll)

Retains only the elements in this collection that are contained in the specified collection. In other words, removes from this Collection all of its elements that are not contained in the specified Collection. Both this collection and the specified collection are treated as sets for the purposes of this operation (that is, duplicate elements are ignored).

Parameters:: c - elements to be retained in this Collection.
Returns:: true if this Collection changed as a result of the call.
See Also:: remove, contains

clear

  public void clear()

Removes all of the elements from this Collection. The Collection will be empty after this call returns.

hashCode

  public int hashCode()

Returns the hash code for the object.

Overrides:: hashCode in class Object