Calling a Java Program from another

Question

Hi,
I am putting together a Java program which will launch other Java programs.
I was thinking of doing this by calling unix scripts from my java program by getting an instance of the Runtime object and then calling the exec method with the script name.
I am just wondering what is the best practice when doing this? i.e., dealing with timeout issues, and errors in the scripts etc.
I have read this article, which is quite good: http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html?page=1
Is there any code available on the web that deals with all of the basic error scenarios?
Is it good practice to use a java program to call another java program? Or is there a better way of doing this?
The main reason I am using java is because I am most familiar with it and I need to connect to a database as well and do some manipulation of results returned.
Any thoughts or suggestions would be much appreciated.
Message was edited by:
LondonJavaDev

Answer 1

Thanks Prometheuzz
Is the main difference between your suggestion and
using the Runtime.getRuntime().exec(cmd) way of doing
things is that in the former both eill run as the
same process (Thread) but in the second scenario the
.getRuntime().exec(cmd) will start a separate new
thread?
Many ThanksCorrect. But you can create a sort of wrapper class for A which implements Runnable and stuff it in it's own thread. If you're dealing with Java code only, I advise you to create threads yourself instead of letting your OS handle them.
Here's a demo:
class Foo {
    public static void main(String[] args) {
        (new Thread(new ARunner())).start();
        B.main(null);
class ARunner implements Runnable {
    public void run() {
        A.main(null);
class A {
    public static void main(String[] args) {
        try {
            Thread.sleep(3000);
        } catch (InterruptedException e) { /* ... */ }
        System.out.println("A");
class B {
    public static void main(String[] args) {
        System.out.println("B");
}Of course, you can create a wrapper for B as well.