How to run a .jar file from inside another java program?

Question

i have a .jar file, which I can run on the command line:

java -jar myFile.jar argument1

I want to save the output of this .jar as a String vari

Answer 1

Take a look at ProcessBuilder:

http://java.sun.com/javase/6/docs/api/java/lang/ProcessBuilder.html

It effectively creates an operating system process which you can then capture the output from using:

process.getInputStream().

The line:

processbuilder.redirectErrorStream(true)

will merge the output stream and the error stream in the following example:

e.g.

public class ProcessBuilderExample {

    public ProcessBuilderExample() {
        // TODO Auto-generated constructor stub
    }
    public static void main(String[] args) throws IOException, InterruptedException {

        ProcessBuilder pb = new ProcessBuilder("java", "-jar", "gscale.jar");
        pb.redirectErrorStream(true);
        pb.directory(new File("F:\\Documents and Settings\\Administrator\\Desktop"));

        System.out.println("Directory: " + pb.directory().getAbsolutePath());
        Process p = pb.start();
        InputStream is = p.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(is));
        for (String line = br.readLine(); line != null; line = br.readLine()) {
                System.out.println( line ); // Or just ignore it
        }
        p.waitFor();                    
    }
}