Package org.apache.lucene.util

Some utility classes.


Interface Summary
Attribute Base interface for attributes.
AttributeReflector This interface is used to reflect contents of AttributeSource or AttributeImpl.
TwoPhaseCommit An interface for implementations that support 2-phase commit.

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.
ByteBlockPool Class that Posting and PostingVector use to write byte streams into shared fixed-size byte[] arrays.
BytesRef Represents byte[], as a slice (offset + length) into an existing byte[].
BytesRefHash BytesRefHash is a special purpose hash-map like data-structure optimized for BytesRef instances.
BytesRefHash.TrackingDirectBytesStartArray A direct BytesRefHash.BytesStartArray that tracks all memory allocation using an AtomicLong instance.
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).
CharsRef Represents char[], as a slice (offset + length) into an existing char[].
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.
DummyConcurrentLock A dummy lock as a replacement for ReentrantLock to disable locking
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.
FixedBitSet BitSet of fixed length (numBits), backed by accessible (FixedBitSet.getBits()) long[], accessed with an int index, implementing Bits and DocIdSet.
IndexableBinaryStringTools Provides support for converting byte sequences to Strings and back again.
IntsRef Represents int[], as a slice (offset + length) into an existing int[].
IOUtils This class emulates the new Java 7 "Try-With-Resources" statement.
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.
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.
RecyclingByteBlockAllocator A ByteBlockPool.Allocator implementation that recycles unused byte blocks in a buffer and reuses them in subsequent calls to RecyclingByteBlockAllocator.getByteBlock().
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().
TwoPhaseCommitTool A utility for executing 2-phase commit on several objects.
TwoPhaseCommitTool.TwoPhaseCommitWrapper A wrapper of a TwoPhaseCommit, which delegates all calls to the wrapped object, passing the specified commitData.
UnicodeUtil Class to encode java's UTF16 char[] into UTF8 byte[] without always allocating a new byte[] as String.getBytes("UTF-8") does.
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
BytesRefHash.MaxBytesLengthExceededException Thrown if a BytesRef exceeds the BytesRefHash limit of ByteBlockPool.BYTE_BLOCK_SIZE-2.
SetOnce.AlreadySetException Thrown when SetOnce.set(Object) is called more than once.
ThreadInterruptedException Thrown by lucene on detecting that Thread.interrupt() had been called.
TwoPhaseCommitTool.CommitFailException Thrown by TwoPhaseCommitTool.execute(TwoPhaseCommit...) when an object fails to commit().
TwoPhaseCommitTool.PrepareCommitFailException Thrown by TwoPhaseCommitTool.execute(TwoPhaseCommit...) when an object fails to prepareCommit().

Package org.apache.lucene.util Description

Some utility classes.

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