Process output only becomes available after the process has finished

Question

I have a Runnable that reads Console output from an externally called exe (see below) and writes it to both a log file and a JTextArea.

But my Runnable doesn\'t show

Answer 1

Just to help the miner - below's a complete minimalistic (left out everything not absolutely necessary) example that indeed works in my context: each line appears in the textArea as read. It's basically using the SwingWorker as suggested by Justin and re-arranged thingies a bit for clarity.

public class ProcessExample {

    public static class ProcessWorker extends SwingWorker {
        private JTextArea ta;
        private List process;

        public ProcessWorker(List command, JTextArea ta) {
            this.process = command;
            this.ta = ta;
        }

        @Override
        protected Void doInBackground() throws Exception {
            Process p = new ProcessBuilder(process).start();
            // Read Process Stream Output and write to LOG file
            BufferedReader is = new BufferedReader(new InputStreamReader(
                    p.getInputStream()));
            String line;
            while ((line = is.readLine()) != null) {
                publish(line);
            }
            is.close();
            return null;
        }

        @Override
        protected void process(List chunks) {
            for (String string : chunks) {
                ta.append(string + "\n");
            }
        }

    }

    private void startProcess(JTextArea ta) {
        ArrayList command = new ArrayList();
        command.add("ping");
        command.add("127.0.0.1");
        new ProcessWorker(command, ta).execute();
    }

    private JComponent getContent() {
        JPanel main = new JPanel(new BorderLayout());
        final JTextArea ta = new JTextArea(20, 60);
        main.add(new JScrollPane(ta));
        Action action = new AbstractAction("Start!") {

            @Override
            public void actionPerformed(ActionEvent e) {
                startProcess(ta);
            }
        };
        main.add(new JButton(action), BorderLayout.SOUTH);
        return main;
    }

    public static void main(String args[]) throws IOException {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame("Example");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                frame.add(new ProcessExample().getContent());
                frame.pack();
                frame.setVisible(true);

            }
        });
    }

}