Java ProcessBuilder

Question

I'm having problems using ProcessBuilder to run a class in my project. My code:

public class Main {
 public static void main(String[] args) {
 try {
 String pathToJar = Main.class.getProtectionDomain().getCodeSource()
 .getLocation().toURI().getPath();
 ArrayList<String> params = new ArrayList<String>(); 
 params.add("javaw");
 params.add("-classpath");
 params.add(pathToJar);
 params.add("Program");
 ProcessBuilder pb = new ProcessBuilder(params);
 Process process = pb.start();
 } catch (Exception e) {
 e.printStackTrace();
 }
 }
}

class Program is in same project (same bin folder) and works fine if ran directly but this way I get the error "Could not find the main class: Program". Where is the error in my code?

Thanks in advance.

[EDIT] I came to the conclution that is some code on my Program class giving error. Basicly only runs with "clean" main. At eclipse, Program class is importing some libraries that are inside a jar file. Don't I need to reference it in ProcessBuilder? If so, how?

• Jim Garrison: What package is class Program in? At params.add("Program"); you need to provide the fully-qualified class name.
• Ciro: none of the classes have package. Anyway put both on package build.test so changed params.add("build.test.Program");. Still same error
• Jim Garrison: Have you tried outputting the value of pathToJar? Is it what you expect?
• Jim Garrison: Edit your post and include a copy/paste of the COMPLETE stacktrace
• Krrose27: Try params.add(System.getProperty("java.class.path").concat(";").concat(pathToJar)); to replace params.add(pathToJar).

Answer 1

In response to your edit:

You can add the current path by switching params.add(pathToJar); with params.add(System.getProperty("java.class.path").concat(";").concat(pathToJar))‌​;.

Answer 2

Where is the error in my code?

(You are launching the javaw executable, so that is not the problem. It is also not that your entry point method's signature is incorrect, because that would have given a different diagnostic.)

The problem is either that the class name is incorrect (e.g. if should be "come.pkg.Program"), or the pathname for the JAR file is incorrect.

---

Assuming that you have eliminated the possibility that the class name is incorrect, my guess is that you are trying to use a relative pathname for the JAR file, but there is some confusion over what the current directory is; i.e. the directory in which the pathname needs to be resolved. Try using an absolute pathname in the classpath parameter.

• Ciro: printed jarpath, its fine. Also tested with package, same error.
• Stephen C: I might be wrong about the entry point. If none of the above helps, show us the signature of the Program class and its main method.