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## org.apache.lucene.codecs.lucene40
Class Lucene40StoredFieldsFormat

    java.lang.Object
      org.apache.lucene.codecs.StoredFieldsFormat
          org.apache.lucene.codecs.lucene40.Lucene40StoredFieldsFormat

    public class Lucene40StoredFieldsFormat

extends StoredFieldsFormat

Lucene 4.0 Stored Fields Format.

Stored fields are represented by two files:

1. The field index, or `.fdx` file.

   This is used to find the location within the field data file of the fields of a particular document. Because it contains fixed-length data, this file may be easily randomly accessed. The position of document n 's field data is the `Uint64` at n*8 in this file.

   This contains, for each document, a pointer to its field data, as follows:

   - FieldIndex (.fdx) --> <Header>, <FieldValuesPosition> SegSize
   - Header --> `CodecHeader`
   - FieldValuesPosition --> `Uint64`

2. The field data, or `.fdt` file.

   This contains the stored fields of each document, as follows:

   - FieldData (.fdt) --> <Header>, <DocFieldData> SegSize
   - Header --> `CodecHeader`
   - DocFieldData --> FieldCount, <FieldNum, Bits, Value> FieldCount
   - FieldCount --> `VInt`
   - FieldNum --> `VInt`
   - Bits --> `Byte`
   - low order bit reserved.
   - second bit is one for fields containing binary data
   - third bit reserved.
   - 4th to 6th bit (mask: 0x7<<3) define the type of a numeric field:
     - all bits in mask are cleared if no numeric field at all
     - 1<<3: Value is Int
     - 2<<3: Value is Long
     - 3<<3: Value is Int as Float (as of `Float.intBitsToFloat(int)`
     - 4<<3: Value is Long as Double (as of `Double.longBitsToDouble(long)`
   - Value --> String | BinaryValue | Int | Long (depending on Bits)
   - BinaryValue --> ValueSize, <`Byte`>^ValueSize
   - ValueSize --> `VInt`

WARNING: This API is experimental and might change in incompatible ways in the next release.

Constructor Summary
`Lucene40StoredFieldsFormat()` Sole constructor.

Method Summary
`StoredFieldsReader` | `fieldsReader(Directory directory, SegmentInfo si, FieldInfos fn, IOContext context)` Returns a `StoredFieldsReader` to load stored fields.
`StoredFieldsWriter` | `fieldsWriter(Directory directory, SegmentInfo si, IOContext context)` Returns a `StoredFieldsWriter` to write stored fields.

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

Constructor Detail

### Lucene40StoredFieldsFormat

    public Lucene40StoredFieldsFormat()

  Sole constructor.

Method Detail

### fieldsReader

    public StoredFieldsReader fieldsReader(Directory directory,
                                           SegmentInfo si,
                                           FieldInfos fn,
                                           IOContext context)
                                    throws IOException

  Description copied from class: `StoredFieldsFormat`
  Returns a `StoredFieldsReader` to load stored fields.

  Specified by:
    `fieldsReader` in class `StoredFieldsFormat`
  Throws:
    `IOException`

### fieldsWriter

    public StoredFieldsWriter fieldsWriter(Directory directory,
                                           SegmentInfo si,
                                           IOContext context)
                                    throws IOException

  Description copied from class: `StoredFieldsFormat`
  Returns a `StoredFieldsWriter` to write stored fields.

  Specified by:
    `fieldsWriter` in class `StoredFieldsFormat`
  Throws:
    `IOException`

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