Ultra-fast, low-level string compression library. Up to 50% reduction.

• 4 bits -> 50% compression rate
• 5 bits -> 38% compression rate
• 6 bits -> 25% compression rate

Fast! Tiny milliseconds to compress a 10 MB string. Check out the benchmarks.

Well tested! See the test directory for usage examples and edge cases.

Compression rate: 50%
Maximum of 16 different chars. Default charset: 0-9, ;, #, -, +, ., ,

byte[] data = str.getBytes(US_ASCII); // Assume data is a 100 megabytes string.
byte[] c = new FourBitAsciiCompressor().compress(data); // c is 50 megabytes.

Compression rate: 38%
Maximum of 32 different chars. Default charset: A-Z, space, ., ,, \, -, @

byte[] data = str.getBytes(US_ASCII); // Assume data is a 100 megabytes string.
byte[] c = new FiveBitAsciiCompressor().compress(data); // c is 62 megabytes.

Compression rate: 25%
Maximum of 64 different chars. Default charset supports A-Z, 0-9, and many punctuation marks which are defined at SixBitAsciiCompressor.DEFAULT_6BIT_CHARSET.

byte[] data = str.getBytes(US_ASCII); // Assume data is a 100 megabytes string.
byte[] c = new SixBitAsciiCompressor().compress(data); // c is 75 megabytes.

Compressors have a set of default characters supported for compression. These are defined in constants DEFAULT_4BIT_CHARSET, DEFAULT_5BIT_CHARSET, and DEFAULT_6BIT_CHARSET. You can define your own character set by using any constructor with the supportedCharset parameter.

It’s useful to validate the input and throw errors when invalid characters are found. You can enable character validation by using any constructor with the throwException parameter. Validation isn’t recommended for production because you will probably be adding dozens of gigabytes to the memory, and you don't want a single invalid character to halt the whole processes. It’s better to occasionally display an incorrect character than to abort the entire operation.

By default, the compressor overwrites the original input byte array to minimize memory usage. Very useful when dealing with big strings, avoiding duplicating them. You can enable input preservation by using any constructor with the preserveOriginal parameter.

Add it to your Maven project:

<dependency>
    <groupId>io.github.dannemann</groupId>
    <artifactId>java-string-compressor</artifactId>
    <version>1.0.0</version>
</dependency>

Gradle:

implementation("io.github.dannemann:java-string-compressor:1.0.0")

Or download the lastest release from: https://github.com/Dannemann/java-string-compressor/releases