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.
Bits Interface for Bitset-like structures.
BytesRefIterator A simple iterator interface for BytesRef iteration.
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.
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
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.
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().
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 Deprecated.  
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.
UnicodeUtil.UTF16Result Holds decoded UTF16 code units.
UnicodeUtil.UTF8Result Holds decoded UTF8 code units.
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
RamUsageEstimator.JvmFeature JVM diagnostic features.
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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