Redraw a TextField during an addActionListener's execution

Question

I'm new to swing, but what I have is a JFrame which contains 4 buttons named A,B,C and D (original I known) and 1 JTextField T
I have the main code:
JFrame f = new JFrame("ContentServer 7.02 Jumpstart Kit");
<some setup code for teh buttons>
JTextField tf2 = new JTextField("", 20);
tf2.setText("Jumpstart Kit Idle");
f.add(tf2);
DisplayTextStatus al = new DisplayTextStatus(tf2);
buttonA.addActionListener(al);
buttonB.addActionListener(al);
buttonC.addActionListener(al);
buttonD.addActionListener(al);
I have an action listener which works for all the buttons that looks like:
class DisplayTextStatus implements ActionListener {
private JTextField tf;
public DisplayTextStatus(JTextField tf) {
this.tf = tf;
so the JTextField is passed into the actionhandler, when the event finishes the JTextField gets updated by:
tf.setBackground (Color.gray);
tf.setText("Kit Newly Configured");
However the the code actually contains 2 updates to the TextField
<random code>
tf.setBackground (Color.red);
tf.setText("In progress");
<random code which takes about 5 minutes>
tf.setBackground (Color.gray);
tf.setText("Kit Newly Configured");
<end of event>
The middle update to the JTextField is not taken, as it appears that the JFRAME is only updated when the action finishes, I need to update this before the action completes . How is this done?
Thanks,
ERIC

Answer 1

Hi,
The important thing to remember about Swing is that it does its painting on the same thread as events are handled on (the Event Dispatch Thread or EDT). In your button event handler you configure the text field, do 5 minutes worth of work, then configure the text field again. The updates to text field are queued up on the EDT and thus will take place after the event handler is done, which is after your 5 minutes of work is completed.
To keep your UI responsive you need to keep your heavy processing off the EDT. Search for SwingWorker, read the API for JProgressBar, and look here:
http://java.sun.com/docs/books/tutorial/uiswing/components/progress.html
Paul
p.s. use the code tags around your source code when posting. And offer up some Dukes too :)