com.sleepycat.bdb.collection
Class StoredContainer

java.lang.Object
  |
  +--com.sleepycat.bdb.collection.StoredContainer

All Implemented Interfaces:

Cloneable

Direct Known Subclasses:

StoredCollection, StoredMap

public abstract class StoredContainer

extends Object

implements Cloneable

A abstract base class for all stored collections and maps. This class provides implementations of methods that are common to the Collection and the Map interfaces, namely clear(), isEmpty() and size().

In addition, this class provides the following methods for stored collections only. Note that the use of these methods is not compatible with the standard Java collections interface.

• isWriteAllowed()
• isIndexed()
• isOrdered()
• areDuplicatesAllowed()
• areDuplicatesOrdered()
• areKeysRenumbered()
• isDirtyReadAllowed()
• isDirtyReadEnabled()
• isAutoCommit()
• isTransactional()

Method Summary

boolean	areDuplicatesAllowed() Returns whether duplicate keys are allowed in this container.
boolean	areDuplicatesOrdered() Returns whether duplicate keys are allowed and sorted by element value.
boolean	areKeysRenumbered() Returns whether keys are renumbered when insertions and deletions occur.
void	clear() Removes all mappings or elements from this map or collection (optional operation).
boolean	isAutoCommit() Returns whether auto-commit is enabled for this container or for its associated DbEnv.
boolean	isDirtyReadAllowed() Returns whether dirty-read is allowed for this container.
boolean	isDirtyReadEnabled() Returns whether dirty-read is enabled for this container.
boolean	isEmpty() Returns true if this map or collection contains no mappings or elements.
boolean	isIndexed() Returns whether this container is a view on a DataIndex rather than directly on a DataStore.
boolean	isOrdered() Returns whether keys are ordered in this container.
boolean	isTransactional() Returns whether the databases underlying this container are transactional.
boolean	isWriteAllowed() Returns true if this is a read-write container or false if this is a read-only container.
int	size() Always throws UnsupportedOperationException.

Methods inherited from class java.lang.Object

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

Method Detail

isWriteAllowed

public final boolean isWriteAllowed()

Returns true if this is a read-write container or false if this is a read-only container. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether write is allowed.

isDirtyReadAllowed

public final boolean isDirtyReadAllowed()

Returns whether dirty-read is allowed for this container. Dirty-read is allowed if Db.DB_DIRTY_READ was specified when opening the database of the underlying Store and Index (if any) for this container. Even when dirty-read is allowed it must specifically be enabled by calling one of the StoredCollections methods. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether dirty-read is allowed.

isDirtyReadEnabled

public final boolean isDirtyReadEnabled()

Returns whether dirty-read is enabled for this container. If dirty-read is enabled, data will be read that is modified but not committed. Dirty-read is disabled by default. This method always returns false if isDirtyReadAllowed() returns false. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether dirty-read is enabled.

isAutoCommit

public final boolean isAutoCommit()

Returns whether auto-commit is enabled for this container or for its associated DbEnv. If auto-commit is enabled, a transaction will be started and committed automatically for each write operation when no transaction is active. Auto-commit only applies to container methods. It does not apply to iterator methods and these always require an explict transaction. Auto-commit is disabled by default for a container but may be enabled for an entire environment using DbEnv.setFlags(int, boolean). This method always returns false if isTransactional() returns false. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether auto-commit is enabled.

isTransactional

public final boolean isTransactional()

Returns whether the databases underlying this container are transactional. Even in a transactional environment, a database will be transactional only if it was opened within a transaction or if the auto-commit option was specified when it was opened. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether the database is transactional.

areDuplicatesAllowed

public final boolean areDuplicatesAllowed()

Returns whether duplicate keys are allowed in this container. Duplicates are optionally allowed for HASH and BTREE databases. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether duplicates are allowed.

areDuplicatesOrdered

public final boolean areDuplicatesOrdered()

Returns whether duplicate keys are allowed and sorted by element value. Duplicates are optionally sorted for HASH and BTREE databases. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether duplicates are ordered.

areKeysRenumbered

public final boolean areKeysRenumbered()

Returns whether keys are renumbered when insertions and deletions occur. Keys are optionally renumbered for RECNO databases. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether keys are renumbered.

isOrdered

public final boolean isOrdered()

Returns whether keys are ordered in this container. Keys are ordered for BTREE, RECNO and QUEUE database. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether keys are ordered.

isIndexed

public final boolean isIndexed()

Returns whether this container is a view on a DataIndex rather than directly on a DataStore. This method does not exist in the standard Map or Collection interfaces.

Returns:

whether the view is indexed.

size

public int size()

Always throws UnsupportedOperationException. The size of a database cannot be obtained reliably or inexpensively. This method therefore violates the Collection.size() and Map.size() interfaces.

Returns:

always throws an exception.

Throws:

UnsupportedOperationException - unconditionally.

isEmpty

public boolean isEmpty()

Returns true if this map or collection contains no mappings or elements. This method conforms to the Collection.isEmpty() and Map.isEmpty() interfaces.

Returns:

whether the container is empty.

Throws:

RuntimeExceptionWrapper - if a DbException is thrown.

clear

public void clear()

Removes all mappings or elements from this map or collection (optional operation). This method conforms to the Collection.clear() and Map.clear() interfaces.

Throws:

UnsupportedOperationException - if the container is read-only.

RuntimeExceptionWrapper - if a DbException is thrown.