getting NoClassDefFound for com/pi4j/io/i2c/I2CFactory - pi4j

Question

I know this question has been asked before but I tried the solutions given in other Threads with no success.
Exception in thread "main" java.lang.NoClassDefFoundError: com/pi4j/io/i2c
/I2CFactory at com.jksoft.rpi.dashpi.pishock.Sensor.setup(Sensor.java:32)
on my windows machine i used maven to get the pi4j dependency and for the I ran the curl statemet shown here (curl -s get.pi4j.com | sudo bash) an then tried to add the classes to the classpath with the command shown on that site: (sudo java -classpath .:classes:/opt/pi4j/lib/'*' ...)
In my case:
sudo java -classpath .:classes:/opt/pi4j/lib/'*':. -jar DashPi-1.0-SNAPSHOT.jar
but it still gives me that error and I dont know whats wrong.
Maybe this happens because pi4j has been installed unter
/opt/pi4j
and my jar is at
/home/pi
Any help would be appreciated!
the code looks as follows:
public Sensor(){
this.setup();
}
private void setup(){
try {
this.bus = I2CFactory.getInstance(I2CBus.BUS_1);
this.device = this.bus.getDevice(0x53);
} catch (IOException ex) {
Logger.getLogger(Sensor.class.getName()).log(Level.SEVERE, null, ex);
}
}

Answer 1

Why are you using the wildcard on that call? It seems that the classpath is wrong and should be something like:
sudo java -classpath .:classes:/opt/pi4j/lib/:. -jar DashPi-1.0-SNAPSHOT.jar