FAQ

• Frequently asked questions (FAQ)
  • Which JVM do you support?
  • Which platforms do you support?
  • What about Android?
  • Why not just use usb4java?
  • Do you deploy using Maven Central?
  • I want to try the latest snapshot release
    • Maven project
    • Gradle project
  • Can I verify the Maven signature myself?
  • How can I know the version of this library programmatically?

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Frequently asked questions (FAQ)

Which JVM do you support?

The current source and target code levels are for Java 8 and above.

Historically this choice was first made when the library was originally written in 2014. At that time Java 7 was the latest and greatest. However issue #11 requested backporting to Java 6 to allow compatibility with older environments. This involved rewinding the JNA library to an earlier version which worked up until 2020 when I was able to revisit the project and perform various updates to fix bugs. This forced the migration from Java 6 (which had long since been EOL by Oracle).

While there are many interesting language features in later versions of Java I will resist the urge to upgrade as this library targets low level operations. Many in the hardware community are very conservative about upgrading to the new shiny unless absolutely necessary.

Which platforms do you support?

If you have a native version of hidapi for your platform then you'll be able to support it.

Here is the current list of platform names with compiled binaries:

• darwin-x86-64 - macOS 64-bit
• darwin-aarch64 - macOS ARM64
• linux-aarch64 - Linux ARMv8 64-bit only
• linux-amd64 - Linux AMD 64-bit only
• linux-arm - Linux ARMv7 hard float 32-bit only
• linux-armel - Linux ARMv5 soft float 32-bit
• linux-riscv64 - Linux RISC-V 64-bit
• linux-x86-64 - Linux x86 64-bit only
• linux-x86 - Linux x86 32-bit only
• win32-x86 - Windows 32-bit only
• win32-x86-64 - Windows 64-bit only
• win32-aarch64 - Windows 64-bit ARM64

What about Android?

In the early days of the project there was some provision for Android but improvements to the accessibility of USB to the devices by the operating system have meant there is no real need for this library there.

Here is a USB HID driver provided by @Chakib-Temal with some discussion in issue #83

Why not just use usb4java?

The usb4java project, while superb, does not support HID devices on macOS and apparently there are no plans to introduce HID support anytime soon.

You will find that trying to claim the USB device on macOS will fail with permissions problems. If you apply a workaround (such as adding a kernel extension) then it will still fall over just a little later in the process. The bottom line is that you must use the hidapi native library to communicate with HID devices on macOS.

Do you deploy using Maven Central?

Yes. A typical entry in a downstream POM would be:

<dependencies>

  <!-- hid4java for cross-platform HID USB -->
  <dependency>
    <groupId>org.hid4java</groupId>
    <artifactId>hid4java</artifactId>
    <version>0.8.0</version>
  </dependency>

</dependencies>

The release deployment procedure follows the standard Maven release process and is based off the master branch. You can find the latest release on the project README.

I want to try the latest snapshot release

Updates to the develop-SNAPSHOT code are pushed fairly regularly via develop branch and act as a form of "pre-release" view of the upcoming code.

In many cases the code contained is not production ready, nor has it been comprehensively reviewed. Use it at your own risk.

Maven project

<repositories>

  <!-- Only include the snapshot repo if you're working with the latest hid4java on develop -->
  <repository>
    <id>hid4java-snapshot</id>
    <url>https://repo.maven.apache.org/maven2</url>
    <!-- These artifacts change frequently during development iterations -->
    <snapshots>
      <updatePolicy>always</updatePolicy>
    </snapshots>
  </repository>

</repositories>

<dependencies>

  <!-- hid4java for cross-platform HID USB -->
  <dependency>
    <groupId>org.hid4java</groupId>
    <artifactId>hid4java</artifactId>
    <version>develop-SNAPSHOT</version>
  </dependency>

</dependencies>

Gradle project

repositories {
    mavenCentral()
}

dependencies {
    implementation('org.hid4java:hid4java:develop-SNAPSHOT')
}

Can I verify the Maven signature myself?

Yes. All artifacts are signed using my personal GPG key with fingerprint 59A81D7B. You will need to download the JAR and ASC files from Maven Central, then issue the following GPG command:

gpg --verify hid4java-0.8.0.jar.asc hid4java-0.8.0.jar

You may need to import my public key beforehand.

How can I know the version of this library programmatically?

The HidServices entry class provides a method getVersion which reads the version from the JAR manifest file. You can test it as follows:

mvn clean package
java -cp target/hid4java-develop-SNAPSHOT.jar org.hid4java.HidServices

The version will reflect what is in the pom.zml so will only be a numeric triplet on the master branch.