Capturing System.out messages

Question

Hey all,
Just wondering what the easiest way to capture System.out messages of a process, and store these messages in an Array, Vector, or a Buffer where I could read these messages line by line later?
Basically one process System.out.println()'s information I need to use as a variable for a second process. Any help would be greatly appreciated.
Thanks!

Answer 1

Here is a class which redirects standard out and err to a JscrollPane.
import java.io.*;
import javax.swing.*;
public class EOutputConsole extends JScrollPane {
  Object lock = new Object();
  final JTextArea text = new JTextArea(10,30);
  PrintStream consoleOut;
  public EOutputConsole() {
    setViewportView(text);
    setupOutput();
   * An extention of PrintStream that notifies a lock
   * as it's executing its write method. This tells
   * an output console that it has input ready.
  class ConsolePrintStream extends PrintStream {
    Object lock;
    public ConsolePrintStream(Object lock, OutputStream out) {
      super(out);
      this.lock = lock;
    public void write(byte[] buf,
                      int off,
                      int len) {
      synchronized(lock) {
        lock.notify();
        super.write(buf,off,len);
   * A class that extends PrintStream to throw away all
   * input sent to it. This is used to supress standard out
   * and speed up test model runs with debugging output
  class NullPrintStream extends PrintStream {
    public NullPrintStream(OutputStream out) {
      super(out);
    public void write(byte[] buf,
                      int off,
                      int len) {
  public void suppressStandardOut() {
    // create a dumby temp file to use as an output stream
    // nothing will ever actually be written to the file
    try {
      File dumbFile = File.createTempFile("notme", "not1337");
      dumbFile.deleteOnExit();
      PrintStream out = new NullPrintStream(new FileOutputStream(dumbFile));
      System.setOut( out );
      System.setErr( out );
    } catch(IOException ioe) {
      System.out.println("Error supressing standard out");
      ioe.printStackTrace();
  public void availableStandardOut() {
    System.setOut( consoleOut );
    System.setErr( consoleOut );
  private void setupOutput() {
    Thread printer = new Thread( new Runnable() {
        public void run() {
          PipedInputStream pipe = new PipedInputStream();
          BufferedReader in = new BufferedReader
            (new InputStreamReader( pipe ));
          try {
            PipedOutputStream pipeOut = new PipedOutputStream(pipe);
            consoleOut = new ConsolePrintStream(lock, pipeOut);
            System.setOut( consoleOut );
            System.setErr( consoleOut );
          catch (Exception e) {
            System.out.println("Failed to create Pipe for System.out");
            e.printStackTrace();
            return;
          try {
            for(;;) {
              while(!in.ready()) {
                synchronized(lock) {
                  lock.wait();
              text.append(in.readLine()+"\n");
              verticalScrollBar.setValue(verticalScrollBar.getMaximum());
          } catch (Exception e) {
            System.out.println(e);
            e.printStackTrace();
    printer.setDaemon(true);
    printer.start();
}