how to do?

[Gnome986]

i wanna write a java editor which can edit file and compile .java to .class.
here is my code:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
class CmdCtrlWindow extends JFrame
{
private JButton runJButton = null;
private JButton cancelJButton = null;
private JButton stopJButton = null;
private JTextField commandJTextField = null;
    private JTextArea stdOutputJTextArea = null;
public CmdCtrlWindow()
{
        initComponents();
        addWindowListener
        (
            new WindowAdapter()
            {
                public void windowClosing( WindowEvent evt )
                {
                    exitForm();
                }
            }
        );
        pack();
        setVisible( true );
}
private void initComponents()
{
Box box = new Box( BoxLayout.X_AXIS );
        runJButton = new JButton( "Run" );
        stopJButton = new JButton( "Stop" );
        cancelJButton = new JButton( "Cancel" );
        commandJTextField = new JTextField( 30 );
        stdOutputJTextArea = new JTextArea( "", 5, 30 );
        stdOutputJTextArea.setEditable( false );
        runJButton.addActionListener
        (
            new ActionListener()
            {
                public void actionPerformed( ActionEvent evt )
                {
                    SwingUtilities.invokeLater
                    (
                        new Runnable()
                        {
                            public void run()
                            {
                                SmartProcess process = new SmartProcess( commandJTextField.getText() );
                                process.execute();
                                //stdOutputJTextArea.setText( process.get );
                                System.out.println( process.getNormalOutput() );
                                System.out.println( "" );
                                System.out.println( process.getErrorOutput() );
                            }
                        }
                    );
                }
            }
        );
        box.add( commandJTextField );
        box.add( runJButton );
        box.add( stopJButton );
        box.add( cancelJButton );
        getContentPane().add( BorderLayout.SOUTH, box );
        getContentPane().add( BorderLayout.CENTER, stdOutputJTextArea );
}
private void exitForm()
{
System.exit( 0 );
}
}
class SmartProcess extends Object
{
    Process     theProcess = null;
    String      error  = null;
    PrintWriter writer = null;
    Reader      reader = null;
    Reader      errReader = null;
    public SmartProcess( String command )
    {
try
    {
theProcess = Runtime.getRuntime().exec( command );
writer = new PrintWriter( theProcess.getOutputStream() );
reader = new InputStreamReader( theProcess.getInputStream() );
errReader = new InputStreamReader( theProcess.getErrorStream() );
    }
catch( IOException ex )
    {
error = "Could not start <"+command+">.";
return;
    }
    }
    public String getError()
    { return error; }
    /** Kills the process but leaves the output streams open.
     *  You can get the last output via getNormalOutput and
     *  getErrorOutput.
     *  @see getNormalOutput
     *  @see getErrorOutput
     */
    public void destroy()
    {
if( theProcess!=null )
    {
// first finish the output to the process
if( writer != null )
    {
writer.close();
writer = null;
    }
destroy();
theProcess = null;
    }
    }
    /** Wait for process to be executed and returns the result.
     *  @return The result of the process or -1 if the process
     *   could not be started or an other error occured.
     */
    public int execute()
    {
// first finish the output to the process
if( writer != null )
    {
writer.close();
writer = null;
    }
if( theProcess != null )
    {
try
    { return theProcess.waitFor(); }
catch( InterruptedException ex )
    { error = "The process was interrupted before it could be finished."; }
    }
return -1;
    }
    /** Closes all streams and kills the process if there is one.
     */
    public void close()
    {
if( writer!=null )
    writer.close();
try
 {
     if( reader!=null )
 reader.close();
     if( errReader!=null )
 errReader.close();
 }
catch ( IOException ex )
    { }
    }
    public void print( String input )
    {
if( writer!=null )
    writer.print( input );
    }
    /** Get the output of the process.
     *  Returns the output of the process.
     *  The same output is never returned twice. You should better
     *  call execute in advance.
     */
    public String getNormalOutput()
    { return getOutput( reader ); }
    /** Get the error output of the process.
     *  Returns the error output of the process.
     *  The same output is never returned twice. You should better
     *  call execute in advance.
     */
    public String getErrorOutput()
    { return getOutput( errReader ); }
    protected String getOutput( Reader reader )
    {
if( reader==null )
    return "";
StringBuffer outputBuffer = new StringBuffer( 10 );
char cBuf[] = new char[128];
int  size   = 0;
try
    {
while( reader.ready() )
    {
size = reader.read( cBuf );
outputBuffer.append( cBuf, 0, size );
    }
    }
catch( IOException e )
    { System.err.println("Error reading output stream\n"); }
return outputBuffer.toString();
    }
}
public class ExecManager
{
    public static void main( String[] args )
    {
        new CmdCtrlWindow();
    }
}

i wanna catch the std output and display it in a JTextArea,but when i run those code,alway lanch a new window.
how can tell me how to do? and who give me some snippet about it,thanks.