Updating jProgressBar

Question

Hi, I have an Iterator in my method that I want to update the jProgressBar after each iteration. The follow snippet of code doesn't update th bar. How to I update the Bar?
    private void xpathExample(java.awt.event.ActionEvent evt) {
        try {
            System.setProperty("javax.xml.xpath.XPathFactory:" + NamespaceConstant.OBJECT_MODEL_SAXON, "net.sf.saxon.xpath.XPathFactoryImpl");
            XPathFactory xpf = XPathFactory.newInstance(NamespaceConstant.OBJECT_MODEL_SAXON);
            XPath xpe = xpf.newXPath();
            returnParser("Loaded XPath Provider: " + xpe.getClass().getName());
            returnParser("Using Saxon 9.0 XPATH");
            InputSource is = new InputSource(new File(this.jTextField1.getText()).toURL().toString());
            SAXSource ss = new SAXSource(is);
            NodeInfo doc = ((XPathEvaluator) xpe).setSource(ss);
            XPathExpression findLine = xpe.compile("//graphic[@boardno]");
            XPathExpression findLocation = xpe.compile("@boardno");
            XPathExpression findSpeaker = xpe.compile("string-join(ancestor-or-self::*/name(), '/')");
            XPathExpression countLines = xpe.compile("count(//graphic[@boardno])");
            String nodeCount = "";
            int i = 0;
            // Set progress
            this.jProgressBar1.setMaximum(1500);
            this.jProgressBar1.setMinimum(0);
            this.jProgressBar1.setValue(0);
            Border border = BorderFactory.createTitledBorder("Reading...");
            int finalCount = 0;
            // Compile the XPath expressions used by the application
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            try {
                List matchedLines = (List) findLine.evaluate(doc, XPathConstants.NODESET);
                // Loop until the user enters "." to end the application
                boolean found = false;
                if (matchedLines != null) {
                    for (Iterator iter = matchedLines.iterator(); iter.hasNext();) {
                        try {
                            found = true;
                            // Get the next matching line
                            NodeInfo line = (NodeInfo) iter.next();
                            // Find where it appears in the play
                            returnParser("File Name: " + findLocation.evaluate(line));
                            // Output the name of the speaker and the content of the line
                            returnParser("Absolute Path: " + findSpeaker.evaluate(line));
                            nodeCount = countLines.evaluate(line);
                            returnParser("Node Count TOTAL:" + nodeCount);
                            i = i + 1;
                            finalCount = Integer.parseInt(nodeCount);
                            // update jProgressBar here!
                            updateBar(i);
                        } catch (XPathExpressionException ex) {
                            Logger.getLogger(startForm.class.getName()).log(Level.SEVERE, null, ex);
                // If no lines were found, say so
                if (!found) {
                    returnParser("XPATH NOT FOUND'");
            } catch (XPathExpressionException ex) {
                Logger.getLogger(startForm.class.getName()).log(Level.SEVERE, null, ex);
            returnParser("Finished.");
        } catch (net.sf.saxon.trans.XPathException ex) {
            Logger.getLogger(startForm.class.getName()).log(Level.SEVERE, null, ex);
        } catch (MalformedURLException ex) {
            Logger.getLogger(startForm.class.getName()).log(Level.SEVERE, null, ex);
        } catch (XPathFactoryConfigurationException ex) {
            Logger.getLogger(startForm.class.getName()).log(Level.SEVERE, null, ex);
        } catch (XPathExpressionException ex) {
            Logger.getLogger(startForm.class.getName()).log(Level.SEVERE, null, ex);
    }Updater Here
public void updateBar(int val) {
        this.jProgressBar1.setValue(val / 1500);
    }Thanks for the help!
Phil

Answer 1

Disclaimer: I haven't read through all of your code.
The short way:
1. run the iteration in a separate Thread
2. wrap the progressBar.setProgress in a SwingUtilities.invokeLater
Probably a better way:
Use a SwingWorker. Perform the iteration in doInBackground. Call publish from doInBackground and update the progress bar from process.
There are simple examples in the SwingWorker API that'll get you going.
luck, db
edit Hello Pete, nice to see we think the same way!
Edited by: Darryl.Burke