JTransforms is the first, open source, multithreaded FFT library written in pure Java. Currently, four types of transforms are available: Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT), Discrete Sine Transform (DST) and Discrete Hartley Transform (DHT). The code is derived from General Purpose FFT Package written by Takuya Ooura and from Java FFTPack written by Baoshe Zhang.
JTransforms-3.1-with-dependencies.jar
JTransforms is available on maven central as
<dependency>
<groupId>com.github.wendykierp</groupId>
<artifactId>JTransforms</artifactId>
<version>3.1</version>
<classifier>with-dependencies</classifier>
</dependency>
Benchmarks are available at JTransforms website.
The documentation is available at apidocs.