ProcessBuilder starting a .class file with parameters

Question

So i have two files: Main.java and Second.java. I wanna work with processes using ProcessBuilder. With cmd i can write "javac Second.java" and "java Second 5". My Second.java looks like that

public static void main(String[] args) {
        System.out.println("Okay");
        System.out.println(Integer.parseInt(args[0])); // I need it just for checking
        System.exit( Integer.parseInt(args[0]));
    }

My second process should return specific exit value (that's why i use System.exit() ). I understood that ProcessBuilder is not a cmd. I tried to run it like that

   Path currentRelativePath = Paths.get("");
   String curDir=currentRelativePath.toAbsolutePath().toString();
   curDir=curDir+"\\src";
   ProcessBuilder PB=new ProcessBuilder("java",curDir, "second", "5");
   try {
                Process process = PB.start();
                process.waitFor();
                System.out.println(process.exitValue());
            }catch (IOException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

But that doesn't work. I think i don't need to create class files exactly in my program i will create them later by cmd. How can i give my ProcessBuilder String[] args, which i need in my Second.main()?

Answer 1

You are executing this command: java directory second 5

That is not a valid invocation of the java command. The syntax is:

java [-options] class [args...]

Passing a class name is correct. Passing a directory is not correct.

You can see the syntax for yourself by running java -h, or by reading the documentation. No need to guess what is allowed.

What you are allowed to do is pass a directory as an argument to the -cp option, which is probably what you intended:

new ProcessBuilder("java", "-cp", curDir, "second", "5");

Be aware that class names are case sensitive. If your class is named Second, you must pass the same name, with a capital S, to your java command:

new ProcessBuilder("java", "-cp", curDir, "Second", "5");
                                           ↑
                                           Uppercase S

All file paths are either absolute paths, or are implicitly relative to the current directory. You don’t need all those lines dealing with currentRelativePath. Just write this:

String curDir = "src";