StoredSortedKeySet (Sleepycat Software, Inc.

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Berkeley DB
version 4.4.20

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com.sleepycat.collections
Class StoredSortedKeySet

java.lang.Object
  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.

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, hashCode, iterator, iterator, join, removeAll, retainAll, toArray, toArray, toList, toString

Methods inherited from class com.sleepycat.collections.StoredContainer

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

Methods inherited from class java.lang.Object

clone, finalize, getClass, 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.