How to validate JLabel in Swing while using FTPClient

Question

I want to update a JLabel each time with the name of the file which I am downloading using FTPClient. I tried repaint(), validate(), revalidate(), first invalidate() and immediately validate()/revalidate() but still nothing is working.

My Code goes as follows:

if(ae.getActionCommand()=="Download"){

    int[] row_indexes=table.getSelectedRows();

    notifylb.setText("Downloading files");
    this.validate();

    for(int i=0;i<row_indexes.length;i++)
    {
         String fn=table.getValueAt(row_indexes[i], 0).toString();  

         notifylb.setText("Downloading: "+fn);  // fn contains filename
         this.validate();

         this.downloadFtpfile(fn);  

    }

    notifylb.setText("SUCCESSFULLY DOWNLOADED FILE(s) !");
    this.validate();
}

Answer 1

@Hovercraft-Full-Of-Eels explain very clear, but if you need the code, here it is how to write it.

final JButton finalButton = button; // this is your button will trigger download
final JLabel finalLabel = finalLabel;
final JTable finalTable = table;


if(ae.getActionCommand().equals("Download"))
{
    finalButton.setEnabled(false); //disable button, so user can not start it for twice until ftp finished.
    Thread thread = new Thread(new Runnable()
    {
        @Override
        public void run()
        {
            int[] row_indexes = finalTable.getSelectedRows();

            SwingUtilities.invokeLater(new Runnable()
            {
                @Override
                public void run()
                {
                    finalLabel.setText("Downloading files");
                }
            });

            for(int i = 0; i < row_indexes.length; i++)
            {
                final String fn = finalTable.getValueAt(row_indexes[i], 0).toString();

                SwingUtilities.invokeLater(new Runnable()
                {
                    @Override
                    public void run()
                    {
                        finalLabel.setText("Downloading: " + fn);  // fn contains filename
                    }
                });

                this.downloadFtpfile(fn);
            }

            SwingUtilities.invokeLater(new Runnable()
            {
                @Override
                public void run()
                {
                    finalLabel.setText("SUCCESSFULLY DOWNLOADED FILE(s) !");
                    finalButton.setEnabled(true); //enable the button
                }
            });
        }
    });
    thread.start();
};