com.sleepycat.collections
Class StoredSortedKeySet

java.lang.Object
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  +--com.sleepycat.collections.StoredContainer
        |
        +--com.sleepycat.collections.StoredCollection
              |
              +--com.sleepycat.collections.StoredKeySet
                    |
                    +--com.sleepycat.collections.StoredSortedKeySet

All Implemented Interfaces:

Cloneable, Collection, Set, SortedSet

public class StoredSortedKeySet

extends StoredKeySet

implements SortedSet

The SortedSet returned by Map.keySet() and which can also be constructed directly if a Map is not needed. Since this collection is a set it only contains one element for each key, even when duplicates are allowed. Key set iterators are therefore particularly useful for enumerating the unique keys of a store or index that allows duplicates.

Note that this class does not conform to the standard Java collections interface in the following ways:

• The StoredContainer.size() method always throws UnsupportedOperationException because, for performance reasons, databases do not maintain their total record count.
• All iterators must be explicitly closed using StoredIterator.close() or StoredIterator.close(java.util.Iterator) to release the underlying database cursor resources.

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

• headSet(Object, boolean)
• tailSet(Object, boolean)
• subSet(Object, boolean, Object, boolean)

Author:

Mark Hayes

Constructor Summary

StoredSortedKeySet(Database database, EntryBinding keyBinding, boolean writeAllowed)
Creates a sorted key set view of a Database.

Method Summary

Comparator	comparator() Returns null since comparators are not supported.
Object	first() Returns the first (lowest) element currently in this sorted set.
SortedSet	headSet(Object toKey) Returns a view of the portion of this sorted set whose elements are strictly less than toKey.
SortedSet	headSet(Object toKey, boolean toInclusive) Returns a view of the portion of this sorted set whose elements are strictly less than toKey, optionally including toKey.
Object	last() Returns the last (highest) element currently in this sorted set.
SortedSet	subSet(Object fromKey, boolean fromInclusive, Object toKey, boolean toInclusive) Returns a view of the portion of this sorted set whose elements are strictly greater than fromKey and strictly less than toKey, optionally including fromKey and toKey.
SortedSet	subSet(Object fromKey, Object toKey) Returns a view of the portion of this sorted set whose elements range from fromKey, inclusive, to toKey, exclusive.
SortedSet	tailSet(Object fromKey) Returns a view of the portion of this sorted set whose elements are greater than or equal to fromKey.
SortedSet	tailSet(Object fromKey, boolean fromInclusive) Returns a view of the portion of this sorted set whose elements are strictly greater than fromKey, optionally including fromKey.

Methods inherited from class com.sleepycat.collections.StoredKeySet

add, contains, remove

Methods inherited from class com.sleepycat.collections.StoredCollection

addAll, containsAll, equals, iterator, iterator, join, removeAll, retainAll, toArray, toArray, toList, toString

Methods inherited from class com.sleepycat.collections.StoredContainer

areDuplicatesAllowed, areDuplicatesOrdered, areKeysRenumbered, clear, isDirtyRead, isDirtyReadAllowed, isEmpty, isOrdered, isSecondary, isTransactional, isWriteAllowed, size

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Set

add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray

Constructor Detail

StoredSortedKeySet

public StoredSortedKeySet(Database database,
                          EntryBinding keyBinding,
                          boolean writeAllowed)

Creates a sorted key set view of a Database.

Parameters:

database - is the Database underlying the new collection.

keyBinding - is the binding used to translate between key buffers and key objects.

writeAllowed - is true to create a read-write collection or false to create a read-only collection.

Throws:

IllegalArgumentException - if formats are not consistently defined or a parameter is invalid.

RuntimeExceptionWrapper - if a DatabaseException is thrown.

Method Detail

comparator

public Comparator comparator()

Returns null since comparators are not supported. The natural ordering of a stored collection is data byte order, whether the data classes implement the Comparable interface or not. This method does not conform to the SortedSet.comparator() interface.

Specified by:

comparator in interface SortedSet

Returns:

null.

first

public Object first()

Returns the first (lowest) element currently in this sorted set. This method conforms to the SortedSet.first() interface.

Specified by:

first in interface SortedSet

Returns:

the first element.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

last

public Object last()

Returns the last (highest) element currently in this sorted set. This method conforms to the SortedSet.last() interface.

Specified by:

last in interface SortedSet

Returns:

the last element.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

headSet

public SortedSet headSet(Object toKey)

Returns a view of the portion of this sorted set whose elements are strictly less than toKey. This method conforms to the SortedSet.headSet(java.lang.Object) interface.

Specified by:

headSet in interface SortedSet

Parameters:

toKey - is the upper bound.

Returns:

the subset.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

headSet

public SortedSet headSet(Object toKey,
                         boolean toInclusive)

Returns a view of the portion of this sorted set whose elements are strictly less than toKey, optionally including toKey. This method does not exist in the standard SortedSet interface.

Parameters:

toKey - is the upper bound.

toInclusive - is true to include toKey.

Returns:

the subset.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

tailSet

public SortedSet tailSet(Object fromKey)

Returns a view of the portion of this sorted set whose elements are greater than or equal to fromKey. This method conforms to the SortedSet.tailSet(java.lang.Object) interface.

Specified by:

tailSet in interface SortedSet

Parameters:

fromKey - is the lower bound.

Returns:

the subset.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

tailSet

public SortedSet tailSet(Object fromKey,
                         boolean fromInclusive)

Returns a view of the portion of this sorted set whose elements are strictly greater than fromKey, optionally including fromKey. This method does not exist in the standard SortedSet interface.

Parameters:

fromKey - is the lower bound.

fromInclusive - is true to include fromKey.

Returns:

the subset.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

subSet

public SortedSet subSet(Object fromKey,
                        Object toKey)

Returns a view of the portion of this sorted set whose elements range from fromKey, inclusive, to toKey, exclusive. This method conforms to the SortedSet.subSet(java.lang.Object, java.lang.Object) interface.

Specified by:

subSet in interface SortedSet

Parameters:

fromKey - is the lower bound.

toKey - is the upper bound.

Returns:

the subset.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.

subSet

public SortedSet subSet(Object fromKey,
                        boolean fromInclusive,
                        Object toKey,
                        boolean toInclusive)

Returns a view of the portion of this sorted set whose elements are strictly greater than fromKey and strictly less than toKey, optionally including fromKey and toKey. This method does not exist in the standard SortedSet interface.

Parameters:

fromKey - is the lower bound.

fromInclusive - is true to include fromKey.

toKey - is the upper bound.

toInclusive - is true to include toKey.

Returns:

the subset.

Throws:

RuntimeExceptionWrapper - if a DatabaseException is thrown.