Package org.apache.commons.compress.compressors.lz77support

Class Parameters.Builder

java.lang.Object
org.apache.commons.compress.compressors.lz77support.Parameters.Builder
Enclosing class:
Parameters
public static class Parameters.Builder extends Object
Builder for Parameters instances.

  • Method Details

    • build

      public Parameters build()
      Creates the Parameters instance.
      Returns:
      the configured Parameters instance.

    • tunedForCompressionRatio

      public Parameters.Builder tunedForCompressionRatio()
      Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression ratio at the cost of compression speed.

      Use this method after configuring "maximum back-reference length".

      Returns:
      the builder

    • tunedForSpeed

      public Parameters.Builder tunedForSpeed()
      Changes the default setting for "nice back-reference length" and "maximum number of candidates" for improved compression speed at the cost of compression ratio.

      Use this method after configuring "maximum back-reference length".

      Returns:
      the builder

    • withLazyMatching

      public Parameters.Builder withLazyMatching(boolean lazy)
      Sets whether lazy matching should be performed.

      Lazy matching means that after a back-reference for a certain position has been found the compressor will try to find a longer match for the next position.

      Lazy matching is enabled by default and disabled when tuning for speed.

      Parameters:
      lazy - whether lazy matching should be performed
      Returns:
      the builder

    • withLazyThreshold

      public Parameters.Builder withLazyThreshold(int threshold)
      Sets the threshold for lazy matching.

      Even if lazy matching is enabled it will not be performed if the length of the back-reference found for the current position is longer than this value.

      Parameters:
      threshold - the threshold for lazy matching
      Returns:
      the builder

    • withMaxBackReferenceLength

      public Parameters.Builder withMaxBackReferenceLength(int maxBackReferenceLength)
      Sets the maximal length of a back-reference.

      It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like SnappyCompressorOutputStream.createParameterBuilder(int).

      Parameters:
      maxBackReferenceLength - maximal length of a back-reference found. A value smaller than minBackReferenceLength is interpreted as minBackReferenceLength. maxBackReferenceLength is capped at windowSize - 1.
      Returns:
      the builder

    • withMaxLiteralLength

      public Parameters.Builder withMaxLiteralLength(int maxLiteralLength)
      Sets the maximal length of a literal block.

      It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like SnappyCompressorOutputStream.createParameterBuilder(int).

      Parameters:
      maxLiteralLength - maximal length of a literal block. Negative numbers and 0 as well as values bigger than windowSize are interpreted as windowSize.
      Returns:
      the builder

    • withMaxNumberOfCandidates

      public Parameters.Builder withMaxNumberOfCandidates(int maxCandidates)
      Sets the maximum number of back-reference candidates that should be consulted.

      This settings can be used to tune the tradeoff between compression speed and compression ratio.

      Parameters:
      maxCandidates - maximum number of back-reference candidates
      Returns:
      the builder

    • withMaxOffset

      public Parameters.Builder withMaxOffset(int maxOffset)
      Sets the maximal offset of a back-reference.

      It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like SnappyCompressorOutputStream.createParameterBuilder(int).

      Parameters:
      maxOffset - maximal offset of a back-reference. A non-positive value as well as values bigger than windowSize - 1 are interpreted as windowSize * - 1.
      Returns:
      the builder

    • withMinBackReferenceLength

      public Parameters.Builder withMinBackReferenceLength(int minBackReferenceLength)
      Sets the minimal length of a back-reference.

      Ensures maxBackReferenceLength is not smaller than minBackReferenceLength.

      It is recommended to not use this method directly but rather tune a pre-configured builder created by a format specific factory like SnappyCompressorOutputStream.createParameterBuilder(int).

      Parameters:
      minBackReferenceLength - the minimal length of a back-reference found. A true minimum of 3 is hard-coded inside of this implementation but bigger lengths can be configured.
      Returns:
      the builder
      Throws:
      IllegalArgumentException - if windowSize is smaller than minBackReferenceLength.

    • withNiceBackReferenceLength

      public Parameters.Builder withNiceBackReferenceLength(int niceLen)
      Sets the "nice length" of a back-reference.

      When a back-references if this size has been found, stop searching for longer back-references.

      This settings can be used to tune the tradeoff between compression speed and compression ratio.

      Parameters:
      niceLen - the "nice length" of a back-reference
      Returns:
      the builder