Follow the official installation instructions of pi4jp（ http://pi4j.com/install.html ）Install

curl -s get.pi4j.com | sudo bash

After the installation, the Java program is executed and the following error is reported

At first, I thought it was a problem with wiringpi. After a long time, I found that it was a problem with the version of the pi4j installation package

The default installation is version 1.1. Raspberry Pie 3 needs version 1.2 to run normally, so you need to manually download the 1.2 installation again

Uninstall 1.1 for automatic installation first

curl -s get.pi4j.com/uninstall | sudo bash

 

install 1.2

wget http://get.pi4j.com/download/pi4j-1.2-SNAPSHOT.deb

Installation

sudo dpkg -i pi4j-1.2-SNAPSHOT.deb

Execute Java again, success