# Lucene 4.2.0 core API

Apache Lucene is a high-performance, full-featured text search engine library.

See: Description

Packages
org.apache.lucene: Top-level package.
org.apache.lucene.analysis: API and code to convert text into indexable/searchable tokens.
org.apache.lucene.analysis.tokenattributes: General-purpose attributes for text analysis.
org.apache.lucene.codecs: Codecs API: API for customization of the encoding and structure of the index.
org.apache.lucene.codecs.compressing: StoredFieldsFormat that allows cross-document and cross-field compression of stored fields.
org.apache.lucene.codecs.lucene3x: Codec to support Lucene 3.x indexes (readonly)
org.apache.lucene.codecs.lucene40: Lucene 4.0 file format.
org.apache.lucene.codecs.lucene41: Lucene 4.1 file format.
org.apache.lucene.codecs.lucene42: Lucene 4.2 file format.
org.apache.lucene.codecs.perfield: Postings format that can delegate to different formats per-field.
org.apache.lucene.document: The logical representation of a `Document` for indexing and searching.
org.apache.lucene.index: Code to maintain and access indices.
org.apache.lucene.search: Code to search indices.
org.apache.lucene.search.payloads: The payloads package provides Query mechanisms for finding and using payloads.
org.apache.lucene.search.similarities: This package contains the various ranking models that can be used in Lucene.
org.apache.lucene.search.spans: The calculus of spans.
org.apache.lucene.store: Binary i/o API, used for all index data.
org.apache.lucene.util: Some utility classes.
org.apache.lucene.util.automaton: Finite-state automaton for regular expressions.
org.apache.lucene.util.fst: Finite state transducers
org.apache.lucene.util.mutable: Comparable object wrappers
org.apache.lucene.util.packed: Packed integer arrays and streams.