## Package org.apache.lucene.util

Some utility classes.

See:
Description

Interface Summary
Attribute: Base interface for attributes.

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 `AttributeImpl`s, and methods to add and get them.
AttributeSource.AttributeFactory: An AttributeFactory creates instances of `AttributeImpl`s.
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.
CloseableThreadLocal: 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.
Constants: Some useful constants.
DocIdBitSet: Simple DocIdSet and DocIdSetIterator backed by a BitSet
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.
MapOfSets: Helper class for keeping Lists of Objects associated with keys.
MemoryModel: Returns primitive memory sizes for estimating RAM usage.
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: A serializable Enum class.
PriorityQueue: 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 `IndexReader`s.
ScorerDocQueue: A ScorerDocQueue maintains a partial ordering of its Scorers such that the least Scorer can always be found in constant time.
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: Borrowed from Cglib.
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
Version: Use by certain classes to match version compatibility across releases of Lucene.

## Package org.apache.lucene.util Description

Some utility classes.

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