Class PopulationCodec
java.lang.Object
org.apache.commons.compress.harmony.pack200.Codec
org.apache.commons.compress.harmony.pack200.PopulationCodec
A PopulationCodec is a Codec that is well suited to encoding data that shows statistical or repetitive patterns, containing for example a few numbers which
are repeated a lot throughout the set, but not necessarily sequentially.
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Field Summary
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Constructor Summary
ConstructorsConstructorDescriptionPopulationCodec(Codec favouredCodec, int l, Codec unfavouredCodec) PopulationCodec(Codec favouredCodec, Codec tokenCodec, Codec unvafouredCodec) -
Method Summary
Modifier and TypeMethodDescriptionintdecode(InputStream in) Decodes a sequence of bytes from the given input stream, returning the value as a long.intdecode(InputStream in, long last) Decodes a sequence of bytes from the given input stream, returning the value as a long.int[]decodeInts(int n, InputStream in) Decodes a sequence ofnvalues fromin.byte[]encode(int value) Encodes a single value into a sequence of bytes.byte[]encode(int[] favoured, int[] tokens, int[] unfavoured) byte[]encode(int value, int last) Encodes a single value into a sequence of bytes.int[]Methods inherited from class org.apache.commons.compress.harmony.pack200.Codec
decodeInts, encode
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Constructor Details
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PopulationCodec
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PopulationCodec
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Method Details
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decode
Description copied from class:CodecDecodes a sequence of bytes from the given input stream, returning the value as a long. Note that this method can only be applied for non-delta encodings.- Specified by:
decodein classCodec- Parameters:
in- the input stream to read from- Returns:
- the value as a long
- Throws:
IOException- if there is a problem reading from the underlying input streamPack200Exception- if the encoding is a delta encoding
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decode
Description copied from class:CodecDecodes a sequence of bytes from the given input stream, returning the value as a long. If this encoding is a delta encoding (d=1) then the previous value must be passed in as a parameter. If it is a non-delta encoding, then it does not matter what value is passed in, so it makes sense for the value to be passed in by default using code similar to:long last = 0; while (condition) { last = codec.decode(in, last); // do something with last }- Specified by:
decodein classCodec- Parameters:
in- the input stream to read fromlast- the previous value read, which must be supplied if the codec is a delta encoding- Returns:
- the value as a long
- Throws:
IOException- if there is a problem reading from the underlying input streamPack200Exception- if there is a problem decoding the value or that the value is invalid
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decodeInts
Description copied from class:CodecDecodes a sequence ofnvalues fromin. This should probably be used in most cases, since some codecs (such asPopulationCodec) only work when the number of values to be read is known.- Overrides:
decodeIntsin classCodec- Parameters:
n- the number of values to decodein- the input stream to read from- Returns:
- an array of
intvalues corresponding to values decoded - Throws:
IOException- if there is a problem reading from the underlying input streamPack200Exception- if there is a problem decoding the value or that the value is invalid
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encode
Description copied from class:CodecEncodes a single value into a sequence of bytes. Note that this method can only be used for non-delta encodings.- Specified by:
encodein classCodec- Parameters:
value- the value to encode- Returns:
- the encoded bytes
- Throws:
Pack200Exception- TODO
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encode
Description copied from class:CodecEncodes a single value into a sequence of bytes.- Specified by:
encodein classCodec- Parameters:
value- the value to encodelast- the previous value encoded (for delta encodings)- Returns:
- the encoded bytes
- Throws:
Pack200Exception- TODO
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encode
- Throws:
Pack200Exception
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getFavoured
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getFavouredCodec
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getTokenCodec
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getUnfavouredCodec
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