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Pi4J / pi4j-v1

DEPRECATED Java I/O library for Raspberry Pi (GPIO, I2C, SPI, UART)
http://www.pi4j.com
Apache License 2.0
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1.4 libs: java.lang.NoClassDefFoundError: com/pi4j/component/relay/Relay #533

Closed kurt-lefevre closed 3 years ago

kurt-lefevre commented 3 years ago

I use the Pi4J libraries to control 2 relays on a PiFace Digital board. Up till version 1.3 everything worked fine. With the 1.3 distro I need following libs: pi4j-core.jar, pi4j-device.jar and pi4j-gpio-extension.jar

I downloaded the 1.4 libs (pi4-distribution) from https://search.maven.org/search?q=com.pi4j and replaced the 1.3 libs with ones in the 1.4 zip.

I use JDK 11.

1.4 gives me following exception at startup: Exception in thread "main" java.lang.NoClassDefFoundError: com/pi4j/component/relay/Relay at be.relaycontrol.RelayControl.(Unknown Source) at be.accesscontrol.AccessController.runController(Unknown Source) at be.accesscontrol.AccessController.main(Unknown Source) Caused by: java.lang.ClassNotFoundException: com.pi4j.component.relay.Relay at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581) at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178) at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)

Any hints what I'm doing wrong?

Tx, Kurt

savageautomate commented 3 years ago

As of Pi4J v1.4 support was dropped for the component interfaces to which includes 'Relay'. See the News/Announcements section on this page: https://pi4j.com/1.4/

You could technically grab that part of v1.3 and include it in your own fork of v1.4 and compile it yourself ... but it's no longer supported or included by the project.

kurt-lefevre commented 3 years ago

Thanks for the answer! This obviuosly explains it.

I took the 1.4 core lib of the distribution and added the device & extension lib in the same lib dir and this works.

I also had a look at the source code. Do I really need the PiFace Digital specific things or can I just manage the relays via the core API through directly accessing the GPIO pins on the PI board?

savageautomate commented 3 years ago

closed.

kurt-lefevre commented 3 years ago

Closed? And what's the answer on my question "Do I really need the PiFace Digital specific things or can I just manage the relays via the core API through directly accessing the GPIO pins on the PI board?"

savageautomate commented 3 years ago

Sorry, I overlooked the question part. My bad ...

I also had a look at the source code. Do I really need the PiFace Digital specific things or can I just manage the relays via the core API through directly accessing the GPIO pins on the PI board?

So .. yes and no.

For any typical basic GPIO exposed directly by the Raspberry Pi 40-pin header that you wish to assert HI or LOW, then yes, you can just use the core GPIO pins.

However, PiFace provides additional GPIO pins that are controlled thru a separate I/O expander chip. At a minimum I think you need these classes to create a custom GPIO provider for the PiFace:
https://github.com/Pi4J/pi4j/tree/release/1.3/pi4j-gpio-extension/src/main/java/com/pi4j/gpio/extension/piface Using the custom PiFace GPIO controller, then you can just use the Pi4J GPIO APIs exposed by the core library. You can probably just copy these two classes to your own project sources and not have to include the older Pi4J v1.3 device/extension JARs.

Here is the example code that can provide an example of how to initialize and use the PiFaceGpioProvider https://github.com/Pi4J/pi4j/blob/3fc6d5d8a5fe9501023aa6568a506334b3696466/pi4j-example/src/main/java/PiFaceGpioExample.java

kurt-lefevre commented 3 years ago

Hi Robert. Confims what I had in mind. Thanks for your answer and the pointers; I'll take it from here.