Java Bindings

The Java language bindings for Darknet/YOLO uses the FFM API (Java Foreign Function and Memory) to perform object detection from within Java applications.

Important

The FFM API requires Java 21 or newer!

For example, on Ubuntu 24.04.3:

# Visit this page to find a recent version of the JDK:  https://www.oracle.com/ca-en/java/technologies/downloads/
wget https://download.oracle.com/java/24/latest/jdk-24_linux-x64_bin.deb
sudo dpkg -i jdk-24_linux-x64_bin.deb
javac --version
javac 24.0.2
java --version
java 24.0.2 2025-07-15

Installing Darknet/YOLO

This project requires that Darknet/YOLO be installed. Before proceeding, please make sure you have built and installed Darknet/YOLO.

The recommended Darknet/YOLO repo to use is the modern one maintained by Stéphane Charette: https://codeberg.org/CCodeRun/darknet#table-of-contents

• If using Windows, you must edit your PATH to include C:/Program Files/Darknet/bin (or wherever you installed it). You must restart your command prompt once you edit the PATH.
• If using Linux, then both darknet and libdarknet.so are installed in a common location, so there should be no need to edit anything further.

Once you've followed the instructions to build and install Darknet/YOLO, confirm that it works correctly by running darknet --version. The output should look somewhat similar to this:

darknet --version
Darknet V5 "Moonlit" v5.0-138-ga061d2f0 [v5]
CUDA runtime version 12000 (v12.0), driver version 12060 (v12.6)
cuDNN version 12020 (v8.9.7), use of half-size floats is ENABLED
=> 0: NVIDIA GeForce RTX 3090 [#8.6], 23.6 GiB
Protobuf 3.21.12, OpenCV 4.6.0, Ubuntu 24.04

Building

The Java bindings for Darknet/YOLO must be compiled. Run the following commands:

cd ~/src/
git clone https://codeberg.org/CCodeRun/DarknetJava.git
cd DarknetJava
mkdir build
javac -d build/ src/Darknet/*.java
java -cp build --enable-native-access=ALL-UNNAMED Darknet.Main

JAR File

To create the .jar file:

cd build
jar --create --verbose --file=Darknet.jar Darknet/*.class

Doxygen Documentation

The Doxygen-generated pages are available here: https://www.ccoderun.ca/programming/doxygen/darknet_java/

To generate the Doxygen output:

cd build
doxygen ../doc/Doxyfile