Package org.apache.lucene.util

Some utility classes.

See: Description

Interface Summary

Interface	Description
Attribute	Base interface for attributes.
AttributeReflector	This interface is used to reflect contents of AttributeSource or AttributeImpl.
Bits	Interface for Bitset-like structures.
BytesRefIterator	A simple iterator interface for BytesRef iteration.
RollingBuffer.Resettable
TwoPhaseCommit	An interface for implementations that support 2-phase commit.

Class Summary

Class	Description
_TestUtil	General utility methods for Lucene unit tests.
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.
Bits.MatchAllBits	Bits impl of the specified length with all bits set.
Bits.MatchNoBits	Bits impl of the specified length with no bits set.
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.
ByteBlockPool.Allocator	Abstract class for allocating and freeing byte blocks.
ByteBlockPool.DirectAllocator	A simple ByteBlockPool.Allocator that never recycles.
ByteBlockPool.DirectTrackingAllocator	A simple ByteBlockPool.Allocator that never recycles, but tracks how much total RAM is in use.
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.BytesStartArray	Manages allocation of the per-term addresses.
BytesRefHash.DirectBytesStartArray	A simple BytesRefHash.BytesStartArray that tracks memory allocation using a private AtomicLong instance.
BytesRefHash.TrackingDirectBytesStartArray	A simple BytesRefHash.BytesStartArray that tracks all memory allocation using a shared 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.
CodecUtil	Utility class for reading and writing versioned headers.
CollectionUtil	Methods for manipulating (sorting) collections.
CommandLineUtil	Class containing some useful methods used by command line tools
Constants	Some useful constants.
Counter	Simple counter class
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	Object providing clone(); the key class must subclass this.
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.
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.
LineFileDocs	Minimal port of contrib/benchmark's LneDocSource + DocMaker, so tests can enum docs from a line file created by contrib/benchmark's WriteLineDoc task
LuceneJUnitDividingSelector	Divides filesets into equal groups
LuceneJUnitResultFormatter	Just like BriefJUnitResultFormatter "brief" bundled with ant, except all formatted text is buffered until the test suite is finished.
LuceneTestCase	Base class for all Lucene unit tests, Junit3 or Junit4 variant.
LuceneTestCaseRunner	optionally filters the tests to be run by TEST_METHOD
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.
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	OpenBitSet with added methods to bulk-update the bits from a DocIdSetIterator.
OpenBitSetIterator	An iterator to iterate over set bits in an OpenBitSet.
PagedBytes	Represents a logical byte[] as a series of pages.
PagedBytes.Reader	Provides methods to read BytesRefs from a frozen PagedBytes.
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 (memory representation) of Java objects.
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().
Rethrow	Sneaky: rethrowing checked exceptions as unchecked ones.
RollingBuffer<T extends RollingBuffer.Resettable>	Acts like forever growing T[], but internally uses a circular buffer to reuse instances of T.
RollingCharBuffer	Acts like a forever growing char[] as you read characters into it from the provided reader, but internally it uses a circular buffer to only hold the characters that haven't been freed yet.
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.
SmartRandom	A random that tracks if its been initialized properly, and throws an exception if it hasn't.
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.
StoreClassNameRule
StringHelper	Methods for manipulating strings.
StringInterner	Subclasses of StringInterner are required to return the same single String object for all equal strings.
SystemPropertiesInvariantRule
SystemPropertiesRestoreRule	Restore system properties from before the nested Statement.
ThrottledIndexOutput	Intentionally slow IndexOutput for testing.
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.
UncaughtExceptionsRule	Subscribes to Thread.setDefaultUncaughtExceptionHandler(java.lang.Thread.UncaughtExceptionHandler) and causes test/ suite failures if uncaught exceptions are detected.
UncaughtExceptionsRule.UncaughtExceptionEntry
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	Holds decoded UTF16 code units.
UnicodeUtil.UTF8Result	Holds decoded UTF8 code units.
UnsafeByteArrayInputStream	This class, much like ByteArrayInputStream uses a given buffer as a source of an InputStream.
UnsafeByteArrayOutputStream	This class is used as a wrapper to a byte array, extending OutputStream.
Vint8	Variable-length encoding of 32-bit integers, into 8-bit bytes.
Vint8.Position	Because Java lacks call-by-reference, this class boxes the decoding position, which is initially set by the caller, and returned after decoding, incremented by the number of bytes processed.
VirtualMethod<C>	A utility for keeping backwards compatibility on previously abstract methods (or similar replacements).
WeakIdentityMap<K,V>	Implements a combination of WeakHashMap and IdentityHashMap.

Enum Summary

Enum	Description
RamUsageEstimator.JvmFeature	JVM diagnostic features.
Version	Use by certain classes to match version compatibility across releases of Lucene.

Exception Summary

Exception	Description
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().

Annotation Types Summary

Annotation Type	Description
LuceneTestCase.Nightly	Annotation for tests that should only be run during nightly builds.

Package org.apache.lucene.util Description

Some utility classes.