How to get JTextArea to show input as it is being added?

[myron schabe]

Hi,
Want I want to do is have a JTextArea display strings as it is being added - sort of like showing progress. The code snippet I have below just (visually)dumps the contents into the text area when the loop is completed. What I want is the JTextArea to visually add the strings line by line as it is looping - so a user know that something is going on rather than a big long wait then a dump. Of course, setText() vs. append() doesn't work either as that doesn't concatentate. Validates or repaints don't seem to help. I am missing something. I can use another widget if it provides the desired affect.
JTextArea textArea = new JTextArea();
for(int i = 0; i <= 10000; i++)
{
textArea.append("blah blah blah blah...\n"); textArea.validate();
scrollPane.validate();
}

Many Thanks!

[Nathan Pruett]

You'll have to add each line in a separate thread... something like this...

import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.io.*;
 
public class LineAdd extends JFrame {
    
    private JTextArea area;
 
    public LineAdd() {
        super( "Line Add" );
        JMenuBar mb = new JMenuBar();
        JMenu file = new JMenu( "File" );
        JMenuItem open = new JMenuItem( "Open" );
        open.addActionListener( new ActionListener() {
            public void actionPerformed( ActionEvent evt ) {
                JFileChooser chooser = new JFileChooser();
                int result = chooser.showOpenDialog( LineAdd.this );
                if ( result == JFileChooser.APPROVE_OPTION && chooser.getSelectedFile() != null ) {
                    try {
                        FileInputStream fis = new FileInputStream( chooser.getSelectedFile() );
                        ThreadedAppend tapp = new ThreadedAppend( fis );
                        tapp.start();
                    }
                    catch ( IOException x ) {
                        area.setText( x.toString() );
                    }
                }
            }
        } );
        file.add( open );
        mb.add( file );
        setJMenuBar( mb );
        area = new JTextArea();
        JScrollPane scroll = new JScrollPane( area );
        getContentPane().add( scroll );
    }
    
    private class ThreadedAppend extends Thread {
        
        private BufferedReader buffer;
        
        public ThreadedAppend( InputStream in ) {
            buffer = new BufferedReader( new InputStreamReader( in ) );
        }
        
        public void run() {
            try {
                area.setText( "" );
                String line = buffer.readLine();
                while ( line != null ) {
                    area.append( line + "\n" );
                    line = buffer.readLine();
                }
            }
            catch ( IOException x ) {
                area.setText( x.toString() );
            }
        }
    }
    
    public static void main( String[] arg ) {
        JFrame f = new LineAdd();
        f.setDefaultCloseOperation( EXIT_ON_CLOSE );
        f.pack();
        f.show();
    }
}