im new to GWT ive been working on it since recently..
i want to know how can i go from "entry point page" ie,ImageViewer.java..
ive been suggested to create the memory by calling constructor on a perticular button
Button button = new Button("New button");
button.addClickHandler(new ClickHandler() {
public void onClick(ClickEvent event)
{
new LookupMaster(); //this is a composite
}
});
but this is not working.. i guess v can only call or get alert messages using this type..
can some one help me.
I'm not sure how to answer, since I have the feeling you're not understanding the basic concepts totally, but that's just my interpretation.
GWT is one html page that via JavaScript methods changes the content of that one page. When you want to display 'another' page you need to do this via methods that update the html dynamically. Since you are just starting with GWT, you might want to read this page on Build User Interfaces to understand the concepts and look at some examples provided with GWT.
Related
When I try to create a new object at clicking a button, the created object does not look okay.
This is what I do:
#UiHandler("button")
protected void onButtonClick(ClickEvent e) {
RootPanel.get().clear();
RootPanel.get().add(new UserLandingPage());
}
The GWT way of switching from a set of widgets to a totally different one is through Activities and Places.
All you need is to follow the google examples on how use the MVP framework.
I collected some demos at the repo below, if you have any doubt don't hesitate to comment and ask further:
https://github.com/jimmyfm/gwt-mvp-examples
Another solution may be to put an HTMLPanel in the root and then switch widgets inside the HTMLPanel by calling
addAndReplaceElement
Does anybody have an idea on how I can accomplish this using Wicket?
I want to display a Wicket odal window automatically when no user activity has been detected for a certain amount of time. I'm thinking of using an AjaxSelfUpdatingBehavior in some way, but I have no clear ideas actually.
Is this possible with Wicket?
Also, you can use some js library not to catch all ajax calls and to be sure, that your user is really afk (even does not touching his mouse).
For example, see this free framework and it's demo.
And (if you using this js framework) in wicket you must handle
ifvisible.idle(function(){
Wicket.Ajax.get({u: '${callbackUrl}'})// This code will work when page goes into idle status
});
You must set ${callbackUrl} from wicket code to let js know what action to proceed in java code. It is not hard to do this. Look here.
This approach is more tricky, but if you implement this, you don't have to worry about users actions at all (he can read site's info and don't click any ajax links, but suddenly he will see modal window).
Yes you can, I use this as autologout function
public class MyTimer extends AbstractAjaxTimerBehavior {
public MyTimer(int seconds) {
this(Duration.seconds(seconds));
}
#Override
protected void onTimer(AjaxRequestTarget target) {
// show your window magic
}
}
Add this to you page (add(new MyTimer(300));) and this will be called after the number of seconds you specify. Make sure to replace the timer with a new one when doing ajax calls, or reset it.
First off, before the flames start, I do know that trying to hinder the back button in the browser is a dumb idea. I would not try to do this, but my business partners are very insistent on it. We are porting an existing .exe to the web and their definition of this is 'run it in a browser' and not "make it a web site". So, fact that it's a bad idea (I agree), here's the question:
Is there a way to ignore or trick the GWT PlaceController / History manager mechanisms so that when the back button is pressed, it just stays on the same page?
I have used Window.addWindowClosingHandler to add a handler which will prompt the user if they want to leave the page and overriden the newItem() method of the defaultHistorian so that no history is tracked at all, but this isn't quite what the business people want.
What they'd like is to just ignore the back button so that nothing happens when it is clicked.
If anyone knows how to do this with GWT, I'd be very grateful.
And I"ve done a lot of google searching and haven't found anything exactly like this question. At least, not close enough to help.
I was able to get GWT to not accumulate any history so that when the user presses the BACK button, they cause an onWindowClosing event to happen and the Browser will prompt them if they want to stay or leave. This will accomplish the goal of not allowing the BACK button to take them back, but it's a bit Draconian. This code does that:
class TvHistorian extends PlaceHistoryHandler.DefaultHistorian
{
#Override
public void newItem(String token, boolean issueEvent) {
// don't do anything - this will prevent history from accumulating
}
}
final PlaceHistoryHandler historyHandler = new PlaceHistoryHandler(historyMapper, new TvHistorian());
I've tried a bunch of stuff including extending the PlaceController.goTo() to save the "lastNormalFlowPlace". Then, I tried to override the History.onValueChange to use this saved Place if it was different than what the event specified. But I think I missed some subtlety because that didn't work as expected.
With the above exception, my code looks almost exactly like what is documented here: http://www.gwtproject.org/doc/latest/DevGuideMvpActivitiesAndPlaces.html#Putting_it_all_together
I have already posted an answer in the same context.
Please have a look at below links:
promt user on backspace and browser backbutton in gwt
how can i get a prompt on url change
Disable back button in GWT
Try with any option:
History.addValueChangeHandler
WindowClosingHandler
Event.addNativePreviewHandler
$wnd.onbeforeunload
--EDIT--
Sample code: (It's working perfectly fine in Firefox, Chrome as well as IE9)
Note: add below code in the beginning of the onModuleLoad() method.
final String initToken = "Place";
History.addValueChangeHandler(new ValueChangeHandler<String>() {
#Override
public void onValueChange(ValueChangeEvent<String> event) {
String token = event.getValue();
if (!initToken.equalsIgnoreCase(token)) {
History.newItem(initToken);
}
}
});
// fire the initial history state.
History.fireCurrentHistoryState();
Note: add checks for other allowed history tokens.
I intend to build a web application where users can enter their time every week and have been struggling to get my head around the concept of a single page in GWT that gets repainted with data depending on the user actions. After researching a lot on this site and google, I found one link that I would like to emulate but dont know how to go about doing it in GWT. Although their source code is available, I dont think it is full and complete. I got some idea from this link - Multiple pages tutorial in Google Web Toolkit (GWT) but again dont know how to implement it into a working version. One small working sample would be great to help me understand and get started.
Could anyone please guide me as to how to achieve the look and feel of the screen with the link below and how the content can be repainted with data from the server ? Would I need to put all the logic in one EntryPoint class ? I would like to have the hyperlinks in the left navigation panel and show the content in the right panel. I seem to be completely lost after a few hours of research.
http://gwt.google.com/samples/Showcase/Showcase.html#!CwHyperlink
Thanks a lot for your help.
Regards,
Sonu.
A single page application layout is actually quite easy to achieve.
The first thing you do is define the general layout, using GWTs layout panels. For your layout, I'd suggest using a DockLayoutPanel.
Content content = new Content();
Button switchContent = new Button(content);
Navigation navigation = new Navigation();
navigation.add(switchContent);
DockLayoutPanel pageLayout = new DockLayoutPanel(Unit.EM);
p.addWest(new HTML(navigation), 7.5);
p.add(new HTML(content));
Here, the width of the navigation panel will be fixed, whereas the content will take the remaining space. You have to pass a reference of the button (or some other widget) which does the switch of the content area, add the button to the navigation area, and so on.
Put this into a class, e.g. called MasterPageFactory:
public class MasterPageFactory {
private MasterPageFactory() {}
public static MasterPage newInstance() {
Content content = new Content();
Button switchContent = new Button(content);
Navigation navigation = new Navigation();
navigation.add(switchContent);
DockLayoutPanel masterPage = new DockLayoutPanel(Unit.EM);
masterPage.addWest(new HTML(navigation), 7.5);
masterPage.add(new HTML(content));
return masterPage;
}
}
Now, in your EntryPoint class, call the factory:
RootLayoutPanel.get().add(MasterPageFactory.newInstance());
This example should get you an idea. Other options would be using a DI framework like Guice or the Command pattern.
Your question is mixing up a couple of concepts. If you want the user to click something that looks like a link, and in reponse the application sends a request to the server and shows a page that looks different than the page they're on, and that page has fresh data that just came from the server, then you want a perfectly normal anchor or form submit button. You don't need anything special or weird from GWT.
The showcase example you referenced lets the user click something that looks like a link, and looks like it loads a new page, even to the point of letting the back button work as expected, but does not actually hit the server to get a new page or new data.
i am developing an application in which i have a logout option at all the forms. When i click that button I have to return to login form which is the first form to be displayed . So i am able to track back to the first from by making a new object of this from by the way this idea is bad to implement because the other froms are also in the stack. My question is how will i go to that first form while the other form objects are distroyed.
The whole idea is about login-logout functionality in winMo app. If somebody can help me with some part of code it will be very great.
Regards,
Madhup
The easiest way is to pass a reference to the Log-in form to all other forms. Avoid creating and destroying forms. Since you know you are going to reuse them, create them only once and then show or hide them.
In log-in form:
if (isLoginSuccessfull) {
newForm.SetParentForm(this);
newForm.Show();
// Do not call Close();
}
In secondary-forms:
public void SetParentForm(Form parent) {
this.parent = parent;
}
// When you need to close the form:
parent.Show();