Capturing command line output to a file possible?

Question

Hi, i am in need of capturing the command line output to a txt file and need some suggestions on how to do it.
I have two classes, class A is the one with all the methods and outputs text to the command line (using System.out.print). class B is the one that calls the methods and needs to record the command line output to a file.
Now the problem i face is not all the output is going to be written to a file and not all the output is going to be displayed on the command line. eg. class B will have a way to select the output mode which is either both to a file and command line or just to a file and display nothing on the command line.
Is what i am asking even possible? Any suggestions would be great!

Answer 1

Here is a class I found on the forum that does basically what you need. Just change the code that is updating a Document to write to a file:
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;
public class ConsoleOutputStream extends OutputStream
     private Document document = null;
     private ByteArrayOutputStream outputStream = new ByteArrayOutputStream(256);
     private PrintStream ps = null;
     public ConsoleOutputStream(Document document, PrintStream ps)
          this.document = document;
          this.ps = ps;
     public void write(int b)
          outputStream.write (b);
     public void flush() throws IOException
          super.flush();
          try
               if (document != null)
                    document.insertString (document.getLength (),
                         new String (outputStream.toByteArray ()), null);
               if (ps != null)
                    ps.write (outputStream.toByteArray ());
               outputStream.reset ();
          catch(Exception e) {}
     public static void main(String[] args)
          JTextArea textArea = new JTextArea();
          JScrollPane scrollPane = new JScrollPane( textArea );
          JFrame frame = new JFrame("Redirect Output");
          frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
          frame.getContentPane().add( scrollPane );
          frame.setSize(300, 600);
          frame.setVisible(true);
          System.setOut( new PrintStream(
               new ConsoleOutputStream (textArea.getDocument (), System.out), true));
          System.setErr( new PrintStream(
               new ConsoleOutputStream (textArea.getDocument (), null), true));
          Timer timer = new Timer(1000, new ActionListener()
               public void actionPerformed(ActionEvent e)
                    System.out.println( new java.util.Date().toString() );
                    System.err.println( System.currentTimeMillis() );
          timer.start();
}