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Pi4J :: Java I/O Library for Raspberry Pi

Build state: GitHub Actions build state

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Project website:

Pi4J diagram

Builds are available from:

Copyright (C) 2012-2021 Pi4J


The Pi4J V2 codebase can be built using Apache Maven 3.6.x. and Java JDK 11. The following command can be used to build the Pi4J V2 JARs:

mvn clean install

Pi4J V2 also includes native libraries that will need to be compiled if you are modifying any native code. Most users will never need to compile the native libraries as these artifacts are automatically downloaded
when building the Pi4J JARs from Maven repositories. One of the following commands can be used to build the Pi4J V2 JARs and Native Libraries:

mvn clean install -Pnative
mvn clean install -Pnative,docker

NOTE: A comprehensive set of build instructions can be found in the Pi4J V2 Documentation.


For full description of the code structure, how to compile... see the "About the code" on our website.

Pi4J V2 code structure

Adding a feature or solving a problem

If you have and idea to extend and improve Pi4J, please first create a ticket to discuss how it fits in the project and how it can be implemented.

If you find a bug, create a ticket, so we are aware of it and others with the same problem can contribute what they already investigated. And the quickest way to get a fix? Try to search for the cause of the problem or even better provide a code fix!

Join the team

You want to become a member of the Pi4J-team? Great idea! Send a short message to with your experience, ideas, and what you would like to contribute to the project.


Pi4J Version 2.0 and later is licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at:

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.


Starting with the Pi4J 2.0 builds, the Pi4J project is prioritizing focus on providing Java programs access, control and communication with the core I/O capabilities of the Raspberry Pi platform.

Read all about it on


For previous 1.x release notes and source code, please see the 1.x GitHub repository.