Problem with initializing a class object

Question

I am trying to write a more modified version of the infamous SimpleBrowser by allowing for the WebBrowser object property to receive a given java.net.URL object.
private final WebBrowser webBrowser = new WebBrowser();
     * Perform setup
    private void setupSimpleBrowser() {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                initObjects();
                initComponents();
     * Initialize objects
    private void initObjects() {
        WebBrowser.setDebug(true); // SET TO TRUE TO SEE trace() DEBUG STATEMENTS
     * Initialize components
    private void initComponents() {
        setTitle(myName);
        generateWebBrowser();
        webAddressTextField = new JTextField(51);
        generateJButton();
        p1 = new JPanel();
        p2 = new JPanel();
        addToPanel();
        forceTFFocus();
        addToFrame();
        showFrame();
     * Generate {@link #webBrowser}
    private void generateWebBrowser() {
        //Use below code to check the status of the navigation process,
        //or register a listener for the notification events.
        webBrowser.addWebBrowserListener(
                new WebBrowserListener() {
            boolean isFirstPage = true;
            public void downloadStarted(WebBrowserEvent event) {;}
            public void downloadCompleted(WebBrowserEvent event) {;}
            public void downloadProgress(WebBrowserEvent event) {;}
            public void downloadError(WebBrowserEvent event) {;}
            public void documentCompleted(WebBrowserEvent event) {
                // Uncomment below code to test getContent()/setContent()/
                // executeScript() APIs.
                // As the setContent() call will invoke this event, which falls
                // into a loop, so check if this event is fired by the first
                // loaded page.
                if (isFirstPage) {
                    testDOMAPI(webBrowser);
                    isFirstPage = false;
            public void titleChange(WebBrowserEvent event) {;}
            public void statusTextChange(WebBrowserEvent event) {;}
            public void windowClose(WebBrowserEvent event) {;}
            public void initializationCompleted(WebBrowserEvent event) {;}
        setWebBrowserURL();
        System.out.println(webBrowser.getURL().toString());
     * Set {@link #webBrowser} with either instantiable {@link java.net.URL} or with {@link #DEFAULT_URL_PATH}
    private void setWebBrowserURL() {
        try {
            URL url = getURL();
            System.out.println("url = " + url);
            String urlPath = getURLPath();
            System.out.println("urlPath = " + urlPath);
            if (url != null) {
                webBrowser.setURL(url);
            } else if (urlPath != null && !urlPath.equals("")) {
                webBrowser.setURL(new URL(urlPath));
            } else {
                System.out.println("setting webBrowser with " + DEFAULT_URL_PATH);
                webBrowser.setURL(new URL(DEFAULT_URL_PATH));
                System.out.println("set up initial homepage of " + DEFAULT_URL_PATH);
        } catch (Exception e) {
            try {
                System.out.println("oops! setting webBrowser with " + DEFAULT_URL_PATH);
                webBrowser.setURL(new URL(DEFAULT_URL_PATH));
            } catch (Exception e2) {
                e2.printStackTrace();
    }However, the moment you leave setWebBrowserURL(), or somehow, within the Thread that is running between setWebBrowserURL() and the System.out.println() line, this happens:
url = null
urlPath = null
setting webBrowser with http://java.net
set up initial homepage of http://java.net
*** Jtrace: You can't call this method before WebBrowser is initialized!
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at com.ppowell.tools.ObjectTools.SimpleBrowser.generateWebBrowser(SimpleBrowser.java:349)
        at com.ppowell.tools.ObjectTools.SimpleBrowser.initComponents(SimpleBrowser.java:384)
        at com.ppowell.tools.ObjectTools.SimpleBrowser.access$600(SimpleBrowser.java:42)
        at com.ppowell.tools.ObjectTools.SimpleBrowser$4.run(SimpleBrowser.java:447)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:597)
        at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:273)
        at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:183)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:173)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:168)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:160)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:121)
*** Jtrace: Process event to native browser: -1, 0,
*** Jtrace: Send data to socket: -1,0,</html><body></html>I can't figure out why webBrowser will not allow for me to determine the given java.net.URL object parameter which will allow for the display of the given URL.
This is based upon http://www.koders.com/java/fidC1435DC25F674DBFCB9C50BE409180D2CAD108E1.aspx
Thanx
Phil

Answer 1

I believe your NullPointerException is happening at
this line (without seeing the line numbers in your
source file, which YOU can do):
>
System.out.println(webBrowser.getURL().toString());
Isn't that line 349, related to this part of the
stack trace?
atcom.ppowell.tools.ObjectTools.SimpleBrowser.generateWe
bBrowser(SimpleBrowser.java:349)
If so, then I'd conclude that webBrowser.getURL() is
returning null, so you can't invoke toString() on
that.It is line 349, it is the line that has System.out.println(webBrowser.getURL().toString()), Removing that line removes the NullPointerException being thrown, however, now I am suddenly unable to use setURL() as it constantly receives a null value when I am clearly sending it a non-null value.
     * Set {@link #webBrowser} with either instantiable {@link java.net.URL} or with {@link #DEFAULT_URL_PATH}
    private void setWebBrowserURL() {
        try {
            URL url = getURL();
            System.out.println("url = " + url);
            String urlPath = getURLPath();
            System.out.println("urlPath = " + urlPath);
            if (url != null) {
                webBrowser.setURL(url);
            } else if (urlPath != null && !urlPath.equals("")) {
                webBrowser.setURL(new URL(urlPath));
            } else {
                System.out.println("setting webBrowser with " + DEFAULT_URL_PATH);
                webBrowser.setURL(new URL(DEFAULT_URL_PATH));
                System.out.println("set up initial homepage of " + DEFAULT_URL_PATH);
        } catch (Exception e) {
            try {
                System.out.println("oops! setting webBrowser with " + DEFAULT_URL_PATH);
                webBrowser.setURL(new URL(DEFAULT_URL_PATH));
            } catch (Exception e2) {
                e2.printStackTrace();
    }Phil