I'm trying to use a custom widget: gwtupload with it's custom handlers. The handlers are defined as interfaces, as in, Interface.OnCustomEventHandler and the method, according to the API, that I want to use is like this code, but I'm not sure how to implement this with uiBinder.:
void onCustomEvent (Interface interface)
Normally for uiBinder I use this code for the regular gwt widgets:
#Widget widget;
#UiHandler("widget")
void onClick(ClickEvent event){
//Handle the event processing here.
}
Presently, when I try this,
#UiHandler("widget")
void onCustomEvent(ICustomInterface customInterface){
...
I get this null pointer exception:
[ERROR] Generator 'com.google.gwt.uibinder.rebind.UiBinderGenerator' threw an exception while rebinding '...ViewImpl.ViewImplUiBinder'
java.lang.NullPointerException
Here is the new code I tried:
public class MUpld extends Composite {
private static MUpldUiBinder uiBinder = GWT.create(MUpldUiBinder.class);
interface MUpldUiBinder extends UiBinder<Widget, MUpld> {
}
#UiField MultiUploader uploader;
public MUpld() {
final IUploader.OnFinishUploaderHandler onFinishUploaderHandler = new IUploader.OnFinishUploaderHandler() {
#Override
public void onFinish(IUploader iUploader) {
if (uploader.getStatus() == Status.SUCCESS){
System.out.println("In the onFinish method!");
}
}
};
initWidget(uiBinder.createAndBindUi(this));
uploader.addOnFinishUploadHandler(onFinishUploaderHandler);
}
}
In the debugger, I saw the handler get attached to the uploader widget I defined, but then the current uploader became a different one once the code moved out of this class. I tried using the final modifier, as that is the only way I know to get a variable into an inner class, but gwt would complain with:
[ERROR] com.cdg.complexityCalculator.client.view.MUpld has no default (zero args) constructor.
To fix this, you can define a #UiFactory method on the UiBinder's owner, or annotate a constructor of MUpld with #UiConstructor.
I wasn't able to get either of those options to work, but I realized I had the last two lines of code switched, so I changed it to what I have now and the handler loaded up with the correct object.
Any ideas as to how to get this to work? Everything else is in place, I just need a way to capture this event after my servlet has finished processing.
When I changed the last two lines of code, the handler got loaded properly. Now the objects are being created with the handler binding to the correct object.
initWidget(uiBinder.createAndBindUi(this));
uploader.addOnFinishUploadHandler(onFinishUploaderHandler);
I had to wait until the uiBinder created the instance of the uploader widget, then I was able to add the handler to it.
One of the tricks I've learned is to add a handler in the constructor for a composite widget you create, that way it's more of an encapsulated component. It handles it's own events.
Related
My problem is with how to stop firing unrelated event of event bus. as I got this solution for Dialog box.
but it does not work in case of where one instance already initialize and try to create new instance of same class.
Just example: A below scroll panel has handler initialized. it used for document preview.
class TestScroll extends ScrollPanel
{
public TestScroll(){
}
implemented onload()
{
// eventBus.addHandler code here.
//here some preview related code
}
unload() method
{
//eventBus remove handler code
}
}
This preview has some data which contains some links that open different preview but with same class and different data structure,
Now The problem is like onUnload ( which contains code of remove handler) event does not load , because other panel opened. that does not mean previous panel unload.
So in that case, twice event handler registered. when one event fired then other event also fired.
Due to that, Preview 1 data shows properly, but after that Preview2 opened and when I close it, I find Preview1=Preview2.
so how can I handle such situation?
As per no of instance created each event fired. but I have to check some unique document id with if condition in event itself.
is there any other ways to stop unrelated event firing?
Edit:
public class Gwteventbus implements EntryPoint {
int i=0;
#Override
public void onModuleLoad() {
TestApp panel=new TestApp();
Button button=new Button("Test Event");
button.addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
TestApp panel=new TestApp();
int j=i;
new AppUtils().EVENT_BUS.fireEventFromSource(new AuthenticationEvent(),""+(j));
i++;
}
});
panel.add(button);
RootPanel.get().add(panel);
}
}
public class AppUtils {
public static EventBus EVENT_BUS = GWT.create(SimpleEventBus.class);
}
public class TestApp extends VerticalPanel{
String testString="";
public TestApp( ) {
AppUtils.EVENT_BUS.addHandler(AuthenticationEvent.TYPE, new AuthenticationEventHandler() {
#Override
public void onAuthenticationChanged(AuthenticationEvent authenticationEvent) {
System.out.println("helloworld"+authenticationEvent.getSource());
}
});
}
}
These are wild guesses as it's difficult to really answer it without code and a clear description.
I'm guessing you have one eventbus for all the panels. So when you register a handler it is registered with that one eventbus. In case you fire an event from one of the panels to the eventbus all panels will receive the event.
To fix this you can either create a new eventbus per panel or check who fired the event with event.getSource().
If this doesn't make sense you probably are reusing a variable or use a static variable which actually should be a new instance or none static variable.
You can use the GwtEventService-Library to fire specific events over a unique domain and every receiver that is registered at this domain receives that events then. You can handle as many different events/domains as you want.
In order to remove a handler attached to the EventBus, you must first store a reference to the HandlerRegistration returned by the addHandler method:
HandlerRegistration hr = eventBus.addHandler(new ClickHandler(){...});
Then you can remove the handler with the removeHandler method:
hr.removeHandler();
A final note worth mentioning is that when using singleton views, like is typical with MVP and GWT Activities and Places, it is best practice to make use of a ResettableEventBus. The eventBus passed to an activity's start() is just such a bus. When the ActivityManager stops the activity, it automatically removes all handlers attached to the ResettableEventBus.
I would strongly recommend reading the GWT Project's documentation on:
Activities and Places
Large scale application development and MVP
I have added some extra functionality to the standard GWT ListBox by extending it like so:
public class FeatureListBox extends ListBox
{
public FeatureListBox()
{
}
public FeatureListBox(boolean isMultipleSelect)
{
super(isMultipleSelect);
}
public FeatureListBox(Element element)
{
super(element);
}
}
Nothing fancy here. However, the Change event is not firing now, or at least the handler (attached per below) is not getting invoked.
FeatureListBox listBox = new FeatureListBox();
listBox.addChangeHandler(new ChangeHandler()
{
public void onChange(ChangeEvent event)
{
// Do something here...
}
});
Any ideas why?
Either remove the no-argument constructor from FeatureListBox or call super() inside it, otherwise the initialization in the superclasses won't happen, which would probably result in what you're seeing.
The problem was in the way I was using my custom list box. In my application I wrap GWT Widgets around existing DOM elements on the page using the static wrap() methods of their widget classes in which the widgets get marked as attached, making them fire events. I didn't do that with my custom list box class originally, so I ended up implementing a static wrap() method similar to the one of the regular ListBox widget and using it in my code. Everything works like a charm now.
I'm using GWT 2.4 with JUnit 4.8.1. When writing my class that extends GWTTestCase, I want to simulate clicking on a button on the page. Currently, in my onModuleLoad method, this button is only a local field ...
public void onModuleLoad() {
final Button submitButton = Button.wrap(Document.get().getElementById(SUBMIT_BUTTON_ID));
...
// Add a handler to send the name to the server
GetHtmlHandler handler = new GetHtmlHandler();
submitButton.addClickHandler(handler);
How do I simulate clicking on this button from the GWTTestCase? Do I have to expose this button as a public member accessor is there a more elegant way to access it? Here is what I have in my test case so far ...
public class GetHtmlTest extends GWTTestCase {
// Entry point class of the GWT application being tested.
private Productplus_gwt productPlusModule;
#Override
public String getModuleName() {
return "com.myco.clearing.productplus.Productplus_gwt";
}
#Before
public void prepareTests() {
productPlusModule = new Productplus_gwt();
productPlusModule.onModuleLoad();
} // setUp
#Test
public void testSuccessEvent() {
// TODO: Simulate clicking on button
} // testSuccessEvent
}
Thanks, - Dave
It can be as easy as buttonElement.click() (or ButtonElement.as(buttonWidget.getElement()).click(), or ButtonElement.as(Document.get().getElementById(SUBMIT_BUTTON_ID)).click())
But remember that a GWTTestCase doesn't run in your own HTML host page, but an empty one, so you'll first have to insert your button within the page before simulating your module's load.
gwt-test-utils seems to be the perfect framework to answer your need. Instead of inheriting from GWTTestCase, extend the gwt-test-utils GwtTest class and implement your click test with the Browser class, like shown in the getting starting guide :
#Test
public void checkClickOnSendMoreThan4chars() {
// Arrange
Browser.fillText(app.nameField, "World");
// Act
Browser.click(app.sendButton);
// Assert
assertTrue(app.dialogBox.isShowing());
assertEquals("", app.errorLabel.getText());
assertEquals("Hello, World!", app.serverResponseLabel.getHTML());
assertEquals("Remote Procedure Call", app.dialogBox.getText());
}
If you want to keep your button private, you'd be able to retrieve it by introspection. But my advice is to make you view's widgets package protected and to write your unit test in the same package so it could access them. It's more convinent and refactoring-friendly.
gwt-test-utils provide introspection convinence. For example, to retrieve the "dialogBox" field which could have been private, you could have do this :
DialogBox dialogBox = GwtReflectionUtils.getPrivateFieldValue(app, "dialogBox");
But note that using GwtReflectionUtils is not mandatory. gwt-test-utils allows you to use ANY java classes in GWT client side tests, without restriction :)
You can do it like this:
YourComposite view = new YourComposite();
RootPanel.get().add(view);
view.getSubmitButton.getElement().<ButtonElement>cast().click();
lets say i have a custom widget which has a ClickHandler. Here's the example:
public class TestWidget extends Composite {
private static TestWidgetUiBinder uiBinder = GWT
.create(TestWidgetUiBinder.class);
interface TestWidgetUiBinder extends UiBinder<Widget, TestWidget> {
}
#UiField
Button button;
public TestWidget(String firstName) {
initWidget(uiBinder.createAndBindUi(this));
button.setText(firstName);
}
#UiHandler("button")
void onClick(ClickEvent e) {
Window.alert("Hello!");
}
}
When i try to add this Widget like this:
TestWidget testWidget = new TestWidget("myTestWidget");
RootPanel.get().add(testWidget);
everything is fine. If i click on my button i get the message i expect.
However if i add it like this:
TestWidget testWidget = new TestWidget("myTestWidget");
RootPanel.getBodyElement().appendChild(testWidget.getElement());
my click event is not being fired. I'm struggeling to understand why.
It would be nice if someone could explain this to me or link me to an resource where i can read this up. Finally i would like to know if it is possible to add the clickhandler afterwards i appended the child event and if that way is recommended. Thanks it advance for help.
kuku
When you call add(), Widget.onAttach() is called on the widget that is being added to the panel. onAttach does some work to register the widget to receive events. appendChild() simply attaches one DOM element to another and does nothing else. You should be able to get events working in the second case by doing this:
Element element = testWidget.getElement();
RootPanel.getBodyElement().appendChild(element);
DOM.sinkEvents(element,
Event.getTypeInt(ClickEvent.getType().getName())
| DOM.getEventsSunk(element);
However, I haven't tested this and I wouldn't recommend that you use it in a real application. Using add() is definitely preferred, using appendChild() in this way has no advantages and may lead to unexpected behaviour.
I'm writing a widget with the following markup:
<g:HTMLPanel ui:field="shortcutPanel" styleName="{style.shortcut}">
<g:Image ui:field="shortcutImage"></g:Image>
<span ui:field="shortcutLabel"></span>
</g:HTMLPanel>
So essentially a div that wraps and image and a label. Now, instead of adding the event handlers on the image/span, I'd like an onClick to be associated with the HTMLPanel. My problem however is that gwt tells me that
shortcutPanel doesn't not have an addClickHandler method associated
So I'm assuming the difference is that HTMLPanel doesn't implement HasClickHandlers or something along that line. I'm wondering then what is the standard way to attach a click handler to a Ui element such as an HTMLPanel or even better, is there such a GWT Widget that is essentially a div wrapper that I can easily attach events to with the #UiHandler annotation.
You are probably looking for FocusPanel - it has all the goodies: HasAllFocusHandlers, HasAllKeyHandlers, HasAllMouseHandlers, HasBlurHandlers, HasClickHandlers.... to name a few :) I find it to be the easiest and best way to attach click handlers to a Panel.
I haven't done this before, but you could do the following:
Create a custom class MyPanel that extends HTMLPanel and implements HasClickHandlers
Add the following method in MyPanel.java
public HandlerRegistration addClickHandler(ClickHandler handler) {
return addDomHandler(handler, ClickEvent.getType());
}
Then replace HTMLPanel with MyPanel in your ui.xml and its corresponding Java implementation.
You can always look at the implementation of HTMLTable to get an understanding of how the event propagation works. It's a Panel and implements HasClickHandlers.
If you want to use the #UiHandler annotation to register event handlers for your custom widget, you need to re-implement the addXXHandler methods. The GWT compiler doesn't seem to find those in superclasses. e.g. if you want to use
#UiHandler("myCustomWidget")
public void handleWidgetSelectionChangeEvent(final SelectionEvent<CountryDts> event) {
...
}
and your CustomWidget extends a class for which this is working, you might need to add the HasSelectionHandlers interface explicitly to your class:
public class CustomComboBox<D> extends ComboBox<D> implements HasSelectionHandlers<D> {
#Override
#SuppressWarnings("pmd.UselessOverridingMethod")
public HandlerRegistration addSelectionHandler(final SelectionHandler<D> handler) {
// GWT Compile doesn't recognize method in supertype for UIHandler
return super.addSelectionHandler(handler);
}
...
}