compile and run java method from another class

Question

Edit: I read the similar Question, but its not working here. I have to check assignments for students. To the assignments have the same name(Ex2.java),they are in different directories. I want my test file to run all the assignments without having to go through each assignment separately.

I tried to compile and run function from another class. But there is no main there.

Lets say that I have this class without main:

public class A {

     public static int num(int x) {
           return x;
     }
}

The main class:

public class B {  
     public static void main(String[] args) throws Exception {  
         Process p = Runtime.getRuntime().exec("javac A.java");
         Process p2 = Runtime.getRuntime().exec("java A");

    }  
} 

Now I want that class B compile and run class A. Try to write something like this in class B:

A.num(x);

Answer 1

Since all files have the same name, I assume they are in different directories, right? Try making a generic test file and create a routine to create a copy of this file in each directory, then execute each of your test files, instead of the assigments.