System Call by Java Application - [change path and run of the other progra]

Question

public class  A {
     public static void main (String[] args)
          System.out.println("Hi");
}I do have above A.java.
I am generating A.class from it.
A.class is in the following directory :
/home/sachin/work/Sample_Directory/bin/hello_filetest/
I have another program which makes System call.
But the problem is B.java is in the different directory :
/home/sachin/work/Sample_Directory/src/hello_filetest/
public class  B {
     public static void main (String[] args) {
Process p1 = Runtime.getRuntime().exec("java A);
            BufferedReader stdInput = new BufferedReader(new
                 InputStreamReader(p1.getInputStream()));
while ((s = stdInput.readLine()) != null) {
                System.out.println(s);
{code}
        So, my question is how to change directory by system calls and execute the program
which is lying in other directory ????
Thank you.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

The following code will call javac on a .java file, which will compile it into a .class file
     public static void javacTest() {
          JFileChooser jf = new JFileChooser();
          if (jf.showOpenDialog(null) != jf.APPROVE_OPTION) return;
          File file = jf.getSelectedFile();
          File dir = file.getParentFile();
          try {
               Process p = Runtime.getRuntime().exec("javac " + file.getName(), null, dir);
               IOUtils.pipe(p.getInputStream(), System.out);
               IOUtils.pipe(p.getErrorStream(), System.out);
          catch (IOException iox) {
               iox.printStackTrace();
     }Is that what you're trying to do, or are you trying to run the compiled (.class) file? Running your .class file should be basically the same as the above, assuming that you are not using any non j2se libraries, except that you need to take into account the package (if package is x.y, you must have file in ...src\x\y\foo.class - call "java x.y.foo" from src)