Found an example:
thanks
giammy

public class HelloClass {
public static void main(String[] args) {
   new HelloClass().say();
   }

public void say() {
  String className = this.getClass().getName().replace('.', '/');
  String classJar = this.getClass().getResource("/" + className +
".class").toString();
  if (classJar.startsWith("jar:")) {
    System.out.println("*** running from jar!");
    }
  System.out.println(classJar);
   
}
}

boolean isRunningInJar() {
    return getClass().getProtectionDomain().getCodeSource()
               .getLocation().getPath().endsWith( ".jar" );
}