java.lang.Object
- org.apache.lucene.index.IndexFileNames

```
public final class IndexFileNames
extends Object
```
This class contains useful constants representing filenames and extensions used by lucene, as well as convenience methods for querying whether a file name matches an extension (matchesExtension), as well as generating file names from a segment name, generation and extension ( fileNameFromGeneration, segmentFileName).

NOTE: This API is for internal purposes only and might change in incompatible ways in the next release.

Field Summary

Fields
Modifier and Type	Field	Description
`static String[]`	`COMPOUND_EXTENSIONS`	File extensions of old-style index files
`static String`	`COMPOUND_FILE_EXTENSION`	Extension of compound file
`static String`	`COMPOUND_FILE_STORE_EXTENSION`	Extension of compound file for doc store files
`static String`	`DELETABLE`	Name of the index deletable file (only used in pre-lockless indices)
`static String`	`DELETES_EXTENSION`	Extension of deletes
`static String`	`FIELD_INFOS_EXTENSION`	Extension of field infos
`static String`	`FIELDS_EXTENSION`	Extension of stored fields file
`static String`	`FIELDS_INDEX_EXTENSION`	Extension of stored fields index file
`static String`	`FREQ_EXTENSION`	Extension of freq postings file
`static String`	`GEN_EXTENSION`	Extension of gen file
`static String[]`	`INDEX_EXTENSIONS`	This array contains all filename extensions used by Lucene's index files, with two exceptions, namely the extension made up from `.f` + a number and from `.s` + a number.
`static String[]`	`INDEX_EXTENSIONS_IN_COMPOUND_FILE`	File extensions that are added to a compound file (same as above, minus "del", "gen", "cfs").
`static String[]`	`NON_STORE_INDEX_EXTENSIONS`
`static String`	`NORMS_EXTENSION`	Extension of norms file
`static String`	`PLAIN_NORMS_EXTENSION`	Extension of plain norms
`static String`	`PROX_EXTENSION`	Extension of prox postings file
`static String`	`SEGMENTS`	Name of the index segment file
`static String`	`SEGMENTS_GEN`	Name of the generation reference file name
`static String`	`SEPARATE_NORMS_EXTENSION`	Extension of separate norms
`static String[]`	`STORE_INDEX_EXTENSIONS`
`static String`	`TERMS_EXTENSION`	Extension of terms file
`static String`	`TERMS_INDEX_EXTENSION`	Extension of terms index file
`static String[]`	`VECTOR_EXTENSIONS`	File extensions for term vector support
`static String`	`VECTORS_DOCUMENTS_EXTENSION`	Extension of vectors documents file
`static String`	`VECTORS_FIELDS_EXTENSION`	Extension of vectors fields file
`static String`	`VECTORS_INDEX_EXTENSION`	Extension of vectors index file

Constructor Summary

Constructors
Constructor Description

IndexFileNames()

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`static String`	`fileNameFromGeneration(String base, String ext, long gen)`	Computes the full file name from base, extension and generation.
`static boolean`	`isDocStoreFile(String fileName)`	Returns true if the provided filename is one of the doc store files (ends with an extension in `STORE_INDEX_EXTENSIONS`).
`static boolean`	`isSeparateNormsFile(String filename)`	Returns true if the given filename ends with the separate norms file pattern: `SEPARATE_NORMS_EXTENSION + "[0-9]+"`.
`static boolean`	`matchesExtension(String filename, String ext)`	Returns true if the given filename ends with the given extension.
`static String`	`segmentFileName(String segmentName, String ext)`	Returns the file name that matches the given segment name and extension.
`static String`	`stripSegmentName(String filename)`	Strips the segment file name out of the given one.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - SEGMENTS
```
public static final String SEGMENTS
```
    Name of the index segment file
    
    See Also:
    
    Constant Field Values
  - SEGMENTS_GEN
```
public static final String SEGMENTS_GEN
```
    Name of the generation reference file name
    
    See Also:
    
    Constant Field Values
  - DELETABLE
```
public static final String DELETABLE
```
    Name of the index deletable file (only used in pre-lockless indices)
    
    See Also:
    
    Constant Field Values
  - NORMS_EXTENSION
```
public static final String NORMS_EXTENSION
```
    Extension of norms file
    
    See Also:
    
    Constant Field Values
  - FREQ_EXTENSION
```
public static final String FREQ_EXTENSION
```
    Extension of freq postings file
    
    See Also:
    
    Constant Field Values
  - PROX_EXTENSION
```
public static final String PROX_EXTENSION
```
    Extension of prox postings file
    
    See Also:
    
    Constant Field Values
  - TERMS_EXTENSION
```
public static final String TERMS_EXTENSION
```
    Extension of terms file
    
    See Also:
    
    Constant Field Values
  - TERMS_INDEX_EXTENSION
```
public static final String TERMS_INDEX_EXTENSION
```
    Extension of terms index file
    
    See Also:
    
    Constant Field Values
  - FIELDS_INDEX_EXTENSION
```
public static final String FIELDS_INDEX_EXTENSION
```
    Extension of stored fields index file
    
    See Also:
    
    Constant Field Values
  - FIELDS_EXTENSION
```
public static final String FIELDS_EXTENSION
```
    Extension of stored fields file
    
    See Also:
    
    Constant Field Values
  - VECTORS_FIELDS_EXTENSION
```
public static final String VECTORS_FIELDS_EXTENSION
```
    Extension of vectors fields file
    
    See Also:
    
    Constant Field Values
  - VECTORS_DOCUMENTS_EXTENSION
```
public static final String VECTORS_DOCUMENTS_EXTENSION
```
    Extension of vectors documents file
    
    See Also:
    
    Constant Field Values
  - VECTORS_INDEX_EXTENSION
```
public static final String VECTORS_INDEX_EXTENSION
```
    Extension of vectors index file
    
    See Also:
    
    Constant Field Values
  - COMPOUND_FILE_EXTENSION
```
public static final String COMPOUND_FILE_EXTENSION
```
    Extension of compound file
    
    See Also:
    
    Constant Field Values
  - COMPOUND_FILE_STORE_EXTENSION
```
public static final String COMPOUND_FILE_STORE_EXTENSION
```
    Extension of compound file for doc store files
    
    See Also:
    
    Constant Field Values
  - DELETES_EXTENSION
```
public static final String DELETES_EXTENSION
```
    Extension of deletes
    
    See Also:
    
    Constant Field Values
  - FIELD_INFOS_EXTENSION
```
public static final String FIELD_INFOS_EXTENSION
```
    Extension of field infos
    
    See Also:
    
    Constant Field Values
  - PLAIN_NORMS_EXTENSION
```
public static final String PLAIN_NORMS_EXTENSION
```
    Extension of plain norms
    
    See Also:
    
    Constant Field Values
  - SEPARATE_NORMS_EXTENSION
```
public static final String SEPARATE_NORMS_EXTENSION
```
    Extension of separate norms
    
    See Also:
    
    Constant Field Values
  - GEN_EXTENSION
```
public static final String GEN_EXTENSION
```
    Extension of gen file
    
    See Also:
    
    Constant Field Values
  - INDEX_EXTENSIONS
```
public static final String[] INDEX_EXTENSIONS
```
    This array contains all filename extensions used by Lucene's index files, with two exceptions, namely the extension made up from .f + a number and from .s + a number. Also note that Lucene's segments_N files do not have any filename extension.
  - INDEX_EXTENSIONS_IN_COMPOUND_FILE
```
public static final String[] INDEX_EXTENSIONS_IN_COMPOUND_FILE
```
    File extensions that are added to a compound file (same as above, minus "del", "gen", "cfs").
  - STORE_INDEX_EXTENSIONS
```
public static final String[] STORE_INDEX_EXTENSIONS
```
  - NON_STORE_INDEX_EXTENSIONS
```
public static final String[] NON_STORE_INDEX_EXTENSIONS
```
  - COMPOUND_EXTENSIONS
```
public static final String[] COMPOUND_EXTENSIONS
```
    File extensions of old-style index files
  - VECTOR_EXTENSIONS
```
public static final String[] VECTOR_EXTENSIONS
```
    File extensions for term vector support
- Constructor Detail
  - IndexFileNames
```
public IndexFileNames()
```
- Method Detail
  - fileNameFromGeneration
```
public static final String fileNameFromGeneration(String base,
                                                  String ext,
                                                  long gen)
```
    Computes the full file name from base, extension and generation. If the generation is -1, the file name is null. If it's 0, the file name is <base>.<ext>. If it's > 0, the file name is <base>_<gen>.<ext>.
    NOTE: .<ext> is added to the name only if ext is not an empty string.
    
    Parameters:
    
    base - main part of the file name
    
    ext - extension of the filename
    
    gen - generation
  - isDocStoreFile
```
public static final boolean isDocStoreFile(String fileName)
```
    Returns true if the provided filename is one of the doc store files (ends with an extension in STORE_INDEX_EXTENSIONS).
  - segmentFileName
```
public static final String segmentFileName(String segmentName,
                                           String ext)
```
    Returns the file name that matches the given segment name and extension. This method takes care to return the full file name in the form <segmentName>.<ext>, therefore you don't need to prefix the extension with a '.'.
    NOTE: .<ext> is added to the result file name only if ext is not empty.
  - matchesExtension
```
public static final boolean matchesExtension(String filename,
                                             String ext)
```
    Returns true if the given filename ends with the given extension. One should provide a pure extension, without '.'.
  - stripSegmentName
```
public static final String stripSegmentName(String filename)
```
    Strips the segment file name out of the given one. If you used segmentFileName(java.lang.String, java.lang.String) or fileNameFromGeneration(java.lang.String, java.lang.String, long) to create your files, then this method simply removes whatever comes before the first '.', or the second '_' (excluding both), in case of deleted docs.
    
    Returns:
    
    the filename with the segment name removed, or the given filename if it does not contain a '.' and '_'.
  - isSeparateNormsFile
```
public static boolean isSeparateNormsFile(String filename)
```
    Returns true if the given filename ends with the separate norms file pattern: SEPARATE_NORMS_EXTENSION + "[0-9]+".

Class IndexFileNames

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

SEGMENTS

SEGMENTS_GEN

DELETABLE

NORMS_EXTENSION

FREQ_EXTENSION

PROX_EXTENSION

TERMS_EXTENSION

TERMS_INDEX_EXTENSION

FIELDS_INDEX_EXTENSION

FIELDS_EXTENSION

VECTORS_FIELDS_EXTENSION

VECTORS_DOCUMENTS_EXTENSION

VECTORS_INDEX_EXTENSION

COMPOUND_FILE_EXTENSION

COMPOUND_FILE_STORE_EXTENSION

DELETES_EXTENSION

FIELD_INFOS_EXTENSION

PLAIN_NORMS_EXTENSION

SEPARATE_NORMS_EXTENSION

GEN_EXTENSION

INDEX_EXTENSIONS

INDEX_EXTENSIONS_IN_COMPOUND_FILE

STORE_INDEX_EXTENSIONS

NON_STORE_INDEX_EXTENSIONS

COMPOUND_EXTENSIONS

VECTOR_EXTENSIONS

Constructor Detail

IndexFileNames

Method Detail

fileNameFromGeneration

isDocStoreFile

segmentFileName

matchesExtension

stripSegmentName

isSeparateNormsFile