Package org.apache.lucene.util

Some utility classes.

See:
Description

Interface Summary

Attribute	Base interface for attributes.
AttributeReflector	This interface is used to reflect contents of AttributeSource or AttributeImpl.

Class Summary

ArrayUtil	Methods for manipulating arrays.
AttributeImpl	Base class for Attributes that can be added to a AttributeSource.
AttributeSource	An AttributeSource contains a list of different AttributeImpls, and methods to add and get them.
AttributeSource.AttributeFactory	An AttributeFactory creates instances of AttributeImpls.
AttributeSource.State	This class holds the state of an AttributeSource.
AverageGuessMemoryModel	An average, best guess, MemoryModel that should work okay on most systems.
BitUtil	A variety of high efficiency bit twiddling routines.
BitVector	Optimized implementation of a vector of bits.
CharacterUtils	CharacterUtils provides a unified interface to Character-related operations to implement backwards compatible character operations based on a Version instance.
CharacterUtils.CharacterBuffer	A simple IO buffer to use with CharacterUtils.fill(CharacterBuffer, Reader).
CloseableThreadLocal<T>	Java's builtin ThreadLocal has a serious flaw: it can take an arbitrarily long amount of time to dereference the things you had stored in it, even once the ThreadLocal instance itself is no longer referenced.
CollectionUtil	Methods for manipulating (sorting) collections.
Constants	Some useful constants.
DocIdBitSet	Simple DocIdSet and DocIdSetIterator backed by a BitSet
DoubleBarrelLRUCache<K extends DoubleBarrelLRUCache.CloneableKey,V>	Simple concurrent LRU cache, using a "double barrel" approach where two ConcurrentHashMaps record entries.
DoubleBarrelLRUCache.CloneableKey
DummyConcurrentLock	A dummy lock as a replacement for ReentrantLock to disable locking
English
FieldCacheSanityChecker	Provides methods for sanity checking that entries in the FieldCache are not wasteful or inconsistent.
FieldCacheSanityChecker.Insanity	Simple container for a collection of related CacheEntry objects that in conjunction with each other represent some "insane" usage of the FieldCache.
FieldCacheSanityChecker.InsanityType	An Enumeration of the different types of "insane" behavior that may be detected in a FieldCache.
IndexableBinaryStringTools	Provides support for converting byte sequences to Strings and back again.
IOUtils
MapBackedSet<E>	A Set implementation that wraps an actual Map based implementation.
MapOfSets<K,V>	Helper class for keeping Lists of Objects associated with keys.
MemoryModel	Returns primitive memory sizes for estimating RAM usage.
NamedThreadFactory	A default ThreadFactory implementation that accepts the name prefix of the created threads as a constructor argument.
NumericUtils	This is a helper class to generate prefix-encoded representations for numerical values and supplies converters to represent float/double values as sortable integers/longs.
NumericUtils.IntRangeBuilder	Expert: Callback for NumericUtils.splitIntRange(org.apache.lucene.util.NumericUtils.IntRangeBuilder, int, int, int).
NumericUtils.LongRangeBuilder	Expert: Callback for NumericUtils.splitLongRange(org.apache.lucene.util.NumericUtils.LongRangeBuilder, int, long, long).
OpenBitSet	An "open" BitSet implementation that allows direct access to the array of words storing the bits.
OpenBitSetDISI
OpenBitSetIterator	An iterator to iterate over set bits in an OpenBitSet.
Parameter	Deprecated. Use Java 5 enum, will be removed in a later Lucene 3.x release.
PriorityQueue<T>	A PriorityQueue maintains a partial ordering of its elements such that the least element can always be found in constant time.
RamUsageEstimator	Estimates the size of a given Object using a given MemoryModel for primitive size information.
ReaderUtil	Common util methods for dealing with IndexReaders.
ReaderUtil.Gather	Recursively visits all sub-readers of a reader.
ScorerDocQueue	A ScorerDocQueue maintains a partial ordering of its Scorers such that the least Scorer can always be found in constant time.
SetOnce<T>	A convenient class which offers a semi-immutable object wrapper implementation which allows one to set the value of an object exactly once, and retrieve it many times.
SimpleStringInterner	Simple lockless and memory barrier free String intern cache that is guaranteed to return the same String instance as String.intern() does.
SmallFloat	Floating point numbers smaller than 32 bits.
SortedVIntList	Stores and iterate on sorted integers in compressed form in RAM.
SorterTemplate	This class was inspired by CGLIB, but provides a better QuickSort algorithm without additional InsertionSort at the end.
StringHelper	Methods for manipulating strings.
StringInterner	Subclasses of StringInterner are required to return the same single String object for all equal strings.
ToStringUtils	Helper methods to ease implementing Object.toString().
UnicodeUtil	Class to encode java's UTF16 char[] into UTF8 byte[] without always allocating a new byte[] as String.getBytes("UTF-8") does.
UnicodeUtil.UTF16Result
UnicodeUtil.UTF8Result
VirtualMethod<C>	A utility for keeping backwards compatibility on previously abstract methods (or similar replacements).

Enum Summary

Version

Use by certain classes to match version compatibility across releases of Lucene.

Exception Summary

SetOnce.AlreadySetException	Thrown when SetOnce.set(Object) is called more than once.
ThreadInterruptedException	Thrown by lucene on detecting that Thread.interrupt() had been called.

Package org.apache.lucene.util Description

Some utility classes.