how to avoid getRuntime.exec() to block when reading inputStream?

I call a class which is located somewhere in a jar file (using java -classpath path/file.jar classname) within my java code.

My problem is when the command genKOSCommand is invalid the call to input.readLine() will block the program. So I added input.ready() to hope avoiding blocking. When I debug the program it's ok. Seem to work. But when don't run it in debug the buffer is never ready.

        // Execute a command with an argument that contains a space
        String[] genKOSCommand = new String[] {
                "java",
                "-classpath",
                Config.XDSI_TEST_KIT_HOME + "/xdsitest/lib/xdsitest.jar;"
                        + Config.XDSI_TEST_KIT_HOME + "/xdsitest/classes",
                "ca.etsmtl.ihe.xdsitest.docsource.SimplePublisher", "-k",
                "C:/Softmedical/Viewer_Test/xdsi-testkit-2.0.4/xdsihome/usr/data/image14.dcm" };

        Process child = Runtime.getRuntime().exec(genKOSCommand);

        Buffere开发者_如何学编程dReader input = new BufferedReader(new InputStreamReader(
                child.getInputStream()), 13107200);

        String line = null;

        if (input.ready()) {
            while ((line = input.readLine()) != null) {
                System.out.println(line);
            }

            try {
                child.waitFor();
            } catch (InterruptedException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

Any advice on how to detect problems with the executed command?

Thank you.

You need to wait in a loop for the BufferedReader to be ready.

while (input.ready() == false) { /* intentional empty space here */ }

while ((line = input.readLine()) != null) {
    System.out.println(line);
}
/* rest of code follows */