LZ4 compression for Java, based on Yann Collet's work available at http://code.google.com/p/lz4/.

This library provides access to two compression methods that both generate a valid LZ4 stream:

• fast scan (LZ4):
  • low memory footprint (~ 16 KB),
  • very fast (fast scan with skipping heuristics in case the input looks incompressible),
  • reasonable compression ratio (depending on the redundancy of the input).
• high compression (LZ4 HC):
  • medium memory footprint (~ 256 KB),
  • rather slow (~ 10 times slower than LZ4),
  • good compression ratio (depending on the size and the redundancy of the input).

The streams produced by those 2 compression algorithms use the same compression format, are very fast to decompress and can be decompressed by the same decompressor instance.

For LZ4 compressors, LZ4 HC compressors and decompressors, 3 implementations are available:

• JNI bindings to the original C implementation by Yann Collet,
• a pure Java port of the compression and decompression algorithms,
• a Java port that uses the sun.misc.Unsafe API in order to achieve compression and decompression speeds similar to the C implementation.

Please have a look at LZ4Factory for more information.

On 64-bits platforms, the Java compressor implementations compress data the same way as the C implementation (meaning that the resulting arrays are identical). However, similarly to the C implementation, compression might return different compressed arrays on a machine of the opposite endianness.

xxhash hashing for Java, based on Yann Collet's work available at http://code.google.com/p/xxhash/.

Similarly to LZ4, 3 implementations are available: JNI bindings, pure Java port and pure Java port that uses sun.misc.Unsafe.

All implementations return the same result for the same input bytes.

• lz4
• xxhash
• changelog

• JDK version 6 or newer,
• ant,
• ivy,
• cpptasks.

If ivy and/or cpptasks are not installed yet, ant can take care of it for you, just run ant ivy-bootstrap cpptasks-bootstrap. Both libraries will be installed under ${user.home}/.ant/lib.

Then run ant. It will compile C and Java code and generate a self-contained JAR file under the dist directory.