VInt8IntEncoder (Lucene 3.6.2 API)
Keywords: org.apache.lucene.util.encoding.VInt8IntEncoder class

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## org.apache.lucene.util.encoding
Class VInt8IntEncoder

    java.lang.Object
      org.apache.lucene.util.encoding.IntEncoder
          org.apache.lucene.util.encoding.VInt8IntEncoder

    public class VInt8IntEncoder

extends IntEncoder

An `IntEncoder` which implements variable length encoding. A number is encoded as follows:

- If it is less than 127 and non-negative, i.e. uses only 7 bits, it is encoded as a single byte: 0bbbbbbb.
- If it occupies more than 7 bits, it is represented as a series of bytes, each byte carrying 7 bits. All but the last byte have the MSB set, the last one has it unset.

Example:

1. n = 117 = 01110101: This has less than 8 significant bits, therefore is encoded as 01110101 = 0x75.
2. n = 100000 = (binary) 11000011010100000. This has 17 significant bits, thus needs three Vint8 bytes. Pad it to a multiple of 7 bits, then split it into chunks of 7 and add an MSB, 0 for the last byte, 1 for the others: 1|0000110 1|0001101 0|0100000 = 0x86 0x8D 0x20.

NOTE: although this encoder is not limited to values ≥ 0, it is not recommended for use with negative values, as their encoding will result in 5 bytes written to the output stream, rather than 4. For such values, either use `SimpleIntEncoder` or write your own version of variable length encoding, which can better handle negative values.

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

Field Summary

Fields inherited from class org.apache.lucene.util.encoding.IntEncoder
`out`

Constructor Summary
`VInt8IntEncoder()`

Method Summary
`IntDecoder` | `createMatchingDecoder()` Returns an `IntDecoder` which matches this encoder.
`void` | `encode(int value)` Encodes an integer to the output stream given in `reInit`
`String` | `toString()`

Methods inherited from class org.apache.lucene.util.encoding.IntEncoder
`close, reInit`

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

Constructor Detail

### VInt8IntEncoder

    public VInt8IntEncoder()

Method Detail

### encode

    public void encode(int value)
                throws IOException

  Description copied from class: `IntEncoder`
  Encodes an integer to the output stream given in `reInit`

  Specified by:
    `encode` in class `IntEncoder`
  Throws:
    `IOException`

### createMatchingDecoder

    public IntDecoder createMatchingDecoder()

  Description copied from class: `IntEncoder`
  Returns an `IntDecoder` which matches this encoder. Every encoder must return an `IntDecoder` and `null` is not a valid value. If an encoder is just a filter, it should at least return its wrapped encoder's matching decoder.

  NOTE: this method should create a new instance of the matching decoder and leave the instance sharing to the caller. Returning the same instance over and over is risky because encoders and decoders are not thread safe.

  Specified by:
    `createMatchingDecoder` in class `IntEncoder`

### toString

    public String toString()

  Overrides:
    `toString` in class `Object`

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