package com.pi4j does not exist

[amastrobera]

Dear Pi4J,

thanks for your library. I had tried the python gpio before, but I have to make the same thing in Java now. I cannot compile the code when using wiringpi module. can you help me build it?

My code (Test.java)

package test;

import com.pi4j.wiringpi;

public class Test {
  public static void main(String[] args) throws InterruptedException {

    if (wiringpi.Gpio.wiringPiSetup() == -1) {
      System.out.println(" ==>> GPIO SETUP FAILED");
      throw new Exception("Gpio.wiringPiSetup() failed");
    }
    System.out.println("<--Pi4J--> GPIO Control Example ... started.");

    wiringpi.Gpio.piBoardRev();
    wiringpi.Gpio.pinMode(7, wiringpi.Gpio.OUTPUT);
    wiringpi.Gpio.pinMode(11, wiringpi.Gpio.OUTPUT);
    wiringpi.Gpio.pinMode(13, wiringpi.Gpio.OUTPUT);
    wiringpi.Gpio.pinMode(15, wiringpi.Gpio.OUTPUT);

    System.out.println("    > backward");
    wiringpi.Gpio.digitalWrite(7, wiringpi.Gpio.HIGH);
    wiringpi.Gpio.digitalWrite(11, wiringpi.Gpio.LOW);
    wiringpi.Gpio.digitalWrite(13, wiringpi.Gpio.HIGH);
    wiringpi.Gpio.digitalWrite(15, wiringpi.Gpio.LOW);

   // bla bla bla some more code 

  }
}

Structure of my project main_dir

• classes
• libs
  • pi4j-core.jar
• test
  • Test.java

I have downloaded the jar files into a lib folder aside the test/Test.java, so I compile it like this (I also compile other stuff depending on jar files this way, and works ... but not wiringpi)

javac -cp classes:/libs/pi4j-core.jar -d classes test/Test.java

Error :

/path/to/Test.java:xx: error: package com.pi4j does not exist 
import com.pi4j.wiringpi; 
               ^                      
/path/to/Test.java:xx: error: package wiringpi does not exist/opt/pi4j
    if (wiringpi.Gpio.wiringPiSetup() == -1) { 
               ^                      
// etc etc for all calls 

[amastrobera]

@savageautomate and @mrdanimal does this have anything to do with wiringpi being deprecated ?

[savageautomate]

Closed.

import com.pi4j.wiringpi; is just the package name. You need to import the actual class you want to use or import all classes from the package using import com.pi4j.wiringpi.*; ... The following works for me:

import com.pi4j.wiringpi.Gpio;

public class Test {
    public static void main(String[] args) throws Exception {

        if (Gpio.wiringPiSetup() == -1) {
            System.out.println(" ==>> GPIO SETUP FAILED");
            throw new Exception("Gpio.wiringPiSetup() failed");
        }
        System.out.println("<--Pi4J--> GPIO Control Example ... started.");

        Gpio.piBoardRev();
        Gpio.pinMode(7, Gpio.OUTPUT);
        Gpio.pinMode(11, Gpio.OUTPUT);
        Gpio.pinMode(13, Gpio.OUTPUT);
        Gpio.pinMode(15, Gpio.OUTPUT);

        System.out.println("    > backward");
        Gpio.digitalWrite(7, Gpio.HIGH);
        Gpio.digitalWrite(11, Gpio.LOW);
        Gpio.digitalWrite(13, Gpio.HIGH);
        Gpio.digitalWrite(15, Gpio.LOW);

        // bla bla bla some more code
    }
}