Develop Reference

Fire Change Event source is NULL in GWT

When clicking an Button it need to perform click action in this action should perform change event at this event source is null
My Code:
Multiview.java
#Override
public void onClick(ClickEvent event) {
if(event.getSource() instanceof PushButton)
{
PushButton pb = (PushButton)event.getSource();
if (id.equals("New")) {
int rowNO = startRow + tableModel.rows() - 1;
Window.selectedRow = rowNO;
Window.selectedNode = m_node;
Window.tabNo = multicomponentVO.tabNo;
Window.tabVO = tabfieldsVO;
Window.selectedqueryID=queryID;
Window.cVO = multicomponentVO;
Window.selectedcVO=multicomponentVO;
fireChange("viewnew");
}
}
private void fireChange(String action) {
this.action = action;
if (changeListeners != null) {
changeListeners.fireChange(new ChangeEvent(){});
}
}
Window.java
#Override
public void onChange(ChangeEvent event) {
Widget sender=(Widget)event.getSource();
if(sender instanceof Multiview)
{
// some stuff
}
My query is When firing change event in multiview.java it fires onchange in window.java but im getting event source is null.
Please anyone help to refine or resolve this query

Several issues are contributing to this.
changeListeners.fireChange(new ChangeEvent(){});
You've taken over how the even is supposed to be fired - instead of actually going through the event wiring that would do it right, you've made an object with no source, passed it to fireChange (which I bet is one of your own methods in changeListeners), though you don't have it listed, unless Multiview.fireChange is calling itself...?), and then are complaining that it has no source! Consider firing either from the widget (I'm assuming Mulitview is a widget), or making a handlerManager/eventBus inside Multiview and using that to send the event.
Next, you are firing a DOM event manually, which is a little weird - this is an event that is meant to be fired from user actions in the browser. Take a look at ValueChangeEvent<T> instead.

How to handle close tab in eclipse RCP 4

I want make a validation when pulse close button of tab in eclipse RCP 4 application and if some validation fails then prevent de close.

If you don't want to use part.setDirty(true) together with an ISaveHandler like greg-449 montioned, you could listen to the model events and correct things there. Something in the direction of this:
public class PreventCloseAddon {
#PostConstruct
public void init(final IEventBroker eventBroker, final EPartService partService) {
EventHandler tbrHandler = new EventHandler() {
#Override
public void handleEvent(Event event) {
if (!UIEvents.isSET(event))
return;
Object element = event.getProperty(UIEvents.EventTags.ELEMENT);
if (element instanceof MPart) {
MPart part = (MPart) element;
if (!part.isToBeRendered()) {
// ... validate here ...
part.setToBeRendered(true);
partService.activate(part);
}
}
}
};
eventBroker.subscribe(UIEvents.UIElement.TOPIC_TOBERENDERED, tbrHandler);
}
}
You should be aware that the part will be rendered again with this code.

How to go back in browser's history with physical back button?

I'm making an app in which I open a BrowserField and the user can navigate further to links present in the web page. The problem is that when I press the physical back button, the previous screen is presented while I want to present the previous page in the BrowserField itself. How to do that? Is that even possible?
Thanks.

You need to use BrowserFieldHistory to go back to previous pages using the canGoBack() and goBack() methods. Just over-ride the keyChar method to control the ESCAPE key input and put your own logic like so:
public boolean keyChar(char key, int status, int time) {
if ( key == Characters.ESCAPE) {
if(yourBrowserField.getHistory().canGoBack()){
yourBrowserField.getHistory().goBack();
}else{
UiApplication.getUiApplication().popScreen(this);
return true;
}
}
}

Yes It is Possible.
Try this code:
public class NewsBrowserScreen extends MainScreen
{
int current_index,popup;
String url;
VerticalFieldManager vertical;
BrowserField browserField;
BrowserFieldConfig browserFieldConfig;
BrowserFieldHistory browserFieldHistory;
public NewsBrowserScreen(int current_index,int popup,String url)
{
this.current_index=current_index;
this.popup=popup;
this.url=url;
createGUI();
}
private void createGUI()
{
vertical=new VerticalFieldManager(VERTICAL_SCROLL|VERTICAL_SCROLLBAR|HORIZONTAL_SCROLL|HORIZONTAL_SCROLLBAR);
browserFieldConfig=new BrowserFieldConfig();
browserFieldConfig.setProperty(BrowserFieldConfig.NAVIGATION_MODE, BrowserFieldConfig.NAVIGATION_MODE_POINTER);
browserField=new BrowserField(browserFieldConfig);
browserFieldHistory=browserField.getHistory();
vertical.add(browserField);
add(vertical);
browserField.requestContent(url);
}
public boolean onClose()
{
if(browserFieldHistory.canGoBack())
{
browserFieldHistory.goBack();
return true;
}
else
{
browserFieldHistory.clearHistory();
return super.onClose();
}
}
}
Enough;

How to Subscribe to GUI Events in Other JFrames

What is the best practice for subscribing to events from another JFrame? For example, I have a "settings" form, and when the user presses okay on the settings form, I want the main form to know about this so it can retrieve the settings.
Thanks.
Here is my ideal interface:
public void showSettingsButton_Click() {
frmSettings sForm = new sForm(this._currentSettings);
//sForm.btnOkay.Click = okayButtonClicked; // What to do here?
sForm.setVisible(true);
}
public void okayButtonClicked(frmSettings sForm) {
this._currentSettings = sForm.getSettings();
}

Someone publishes an Event, that something has changed, here the settings. A subscriber that registered for this specifig event, gets notified about it and can do his work, here get the settings. This is called publisher/subscriber.
For this you can use Eventbus or implementing something smaller on your own.

One approach is to have only a single JFrame. All the other 'free floating top level containers' could be modal dialogs. Access the the main GUI will be blocked until the current dialog is dismissed, and the code in the main frame can check the settings of the dialog after it is dismissed.

For anyone interested, here is what I ended up going with. I'm not sure if it's the best way, but it is working for my purposes.
// Method called when the "Show Settings" button is pressed from the main JFrame
private void showSettingsButton_Click() {
// Create new settings form and populate with my settings
frmSettings sForm = new frmSettings(this.mySettings);
// Get the "Save" button and register for its click event...
JButton btnSave = sForm.getSaveButton();
btnSave.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent evt) {
SaveSettings(sForm);
}
});
// Show the settings form
sForm.setVisible(true);
}
// Method called whenever the save button is clicked on the settings form
private void SaveSettings(frmSettings sForm) {
// Get the new settings and assign them to the local member
Settings newSettings = sForm.getSettings();
this.mySettings = newSettings;
}
And if, like me, you are coming from a .NET perspective, here is the C# version:
private void showSettingsButton_Click(object sender, EventArgs e)
{
frmSettings sForm = new frmSettings(this.mySettings);
sForm.btnSave += new EventHandler(SaveSettings);
sForm.Show();
}
private void SaveSettings(object sender, EventArgs e)
{
frmSettings sForm = (frmSettings)sender; // This isn't the exact cast you need..
Settings newSettings = sForm.Settings;
this.mySettings = newSettings;
}

How to defeat browser dialog popup when calling Wicket setResponsePage() from modal window?

How to defeat IE and Firefox dialog popup when trying to setResponsePage() from a wicket modalWindow per below. Dialog popup demands an answer to: "This page is asking you to confirm that you want to leave - data you have entered may not be saved."
AjaxLink signInContainer = new AjaxLink("signInContainer") {
#Override
public void onClick(AjaxRequestTarget target) {
target.appendJavascript("Wicket.Window.unloadConfirmation = false;");
modalWindow.close(target);
setResponsePage(SignInPage.class);
modalWindow.close(target);
}
};
-Rich

In wicket 6.x and above you can simply set showUnloadConfirmation to false:
final ModalWindow modalWindow = new ModalWindow("modalWindow");
modalWindow.showUnloadConfirmation(false);

target.appendJavascript("Wicket.Window.unloadConfirmation = false;"); doesn't work because it must run before modal.show(target);.
You could either prepend, instead of append, the script, when opening the window:
add(new AjaxLink<Void>("show") {
#Override
public void onClick(AjaxRequestTarget target) {
target.prependJavascript("Wicket.Window.unloadConfirmation = false;");
modal.show(target);
}
});
or add a behavior, to execute it on onload:
modal.add(new AbstractBehavior() {
#Override
public void renderHead(IHeaderResponse response) {
response.renderOnLoadJavascript("Wicket.Window.unloadConfirmation = false;");
}
});
But, it must be called before opening the modal window, not when navigating away from the page (setResponsePage()).

I believe setResponsePage() should be accompanied by some other methods to behave properly. For example, I often include setRedirect(true) when using this technique. I'm not sure what all is going on behind the scenes there, but perhaps try that.

EDIT: This is a hack, use the alternative described in my other answer.
Try this:
public void onClick(AjaxRequestTarget target) {
modal.close(target);
CharSequence url = urlFor(HomePage.class, new PageParameters("gone=true"));
target.appendJavascript("window.location='" + url + "';");
}