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GXT - send forms on enter, project-wide

I have an application which uses GXT and contains ±30 forms. I would like to make these forms so that when the user hits enter in a text field, the form gets submitted, like a regular browser form would.
I know I can add a key press listener to every text field, which would invoke the submit after enter is pressed, but since I want to apply this to every field in every form I am not sure if this is ideal.
Is there a simpler way to implement this in the entire application?
If not, which pattern should I use to add this functionality to every field? I can extend the TextField class, add the functionality in the child class and use the child class in the application. Or I can create a factory for the text field class which would also add the listener to the field. Or is there some other way, Decorator perhaps? I was wondering which of these approaches, if any, is generally preferred.

I would try something like this:
Event.addNativePreviewHandler(new NativePreviewHandler() {
#Override
public void onPreviewNativeEvent(NativePreviewEvent event) {
if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_ENTER) {
if (event.getNativeEvent().getEventTarget() != null) {
Element as = Element.as(event.getNativeEvent().getEventTarget());
if (as.getTagName().toLowerCase().equals("input") ||
as.getTagName().toLowerCase().equals("textarea")) {
// TODO submit data;
}
}
}
}
});
Every time someone hits the Enter Key and the cursor is placed on a input- or textarea-tag, you will get the control and can submit your data.

I don't think there is a way to do what you're asking directly in the GXT library. I do want to stress that extending the TextField class just to add an event handler to it is not the correct way to handle this. Event handlers are based on the composition of a class. It would be like extending a class with a List field just to add another element into the list.
A singleton factory class that created and initialises the Textfield for you would be the cleanest solution, in my opinion. It would allow you to effectively change defaults and add other handlers as required at a later time in a single place if requirements change.

You can try it with GWT JSNI also.
Steps to follow:
define a function in JavaScript that is called on Enter key press
call GWT JSNI from above JavaScript function that is exported at the time of onModuleLoad using GWT JSNI
get the Element from where this event is triggered and finally submit the form based on its tag name or Id
Sample code:
HTML/JSP:
<script>
window.onkeydown = keydown;
function keydown(event) {
if (event.which == 13) {
formSubmit(event.target);
}
}
</script>
JAVA(Entry Point):
import com.google.gwt.dom.client.Element;
public void onModuleLoad() {
exportFormSubmit();
...
}
public static void formSubmit(Element element) {
Window.alert("element tag name:" + element.getTagName() + "form ID:"
+ element.getParentElement().getId());
}
public static native void exportFormSubmit() /*-{
$wnd.formSubmit = $entry(#com.x.y.z.client.GWTTestProject::formSubmit(Lcom/google/gwt/dom/client/Element;));
}-*/;

GWT equivalent of jQuery change() for form elements

Can anyone tell me whether there is an equivalent method in GWT like change in jQuery for form elements like radio-buttons, checkboxes, etc, which is fired the moment any such button is checked or unchecked? If so, how do I use it? I found a method like addValueChangeHandler in the Google docs, but apart from providing the prototype, there is no working example.
Specifically, if I want a handler which will wait for a checkbox being checked or unchecked, and accordingly pop up an alert like A checkbox has been checked!!, along with that buttons accompanying text.

CheckBox newOption = new CheckBox();
newOption.setText("Check to see alert");
newOption.addValueChangeHandler(new ValueChangeHandler<Boolean>() {
#Override
public void onValueChange(ValueChangeEvent<Boolean> event) {
if (event.getValue()) {
Window.alert("Checkbox is checked!");
} else {
Window.alert("Checkbox is unchecked!");
}
}
});

java save changes

I have an application which consists mainly in a JList being displayed on the screen. I would like that everytime I make a change to the AbstractListModel(adding or removing items to the list) , to somehow notify the app that changes have been made and modify the JFrame's title to something like frame_title[unsaved]. After I would save the app, the [unsaved] tag would go away.
I think maybe using the observer/observable technique would do the job but I am not sure how to do it. Maybe there is something much more appropriate to my problem? I am new to java new to java so that is why I came here asking for help. Thanks.
UPDATE : I can't really use the Observer-pattern in my case because I am already extending the AbstractListModel class.

Use this:
AbstractListModel model = ...;
model.addListDataListener(new ListDataListener() {
public void intervalAdded(ListDataEvent e) {
}
public void intervalRemoved(ListDataEvent e) {
}
public void contentsChanged(ListDataEvent e) {
}
});

GWT SuggestBox: How do I force the SuggestBox to select the first item in the suggestion list?

I have a textbox and one suggestbox. I attach a value change and key up handler to the text box such that whatever the user types (or pastes) into the text box is echo-ed inside the suggestbox. I can get the suggestbox to display the suggestion list by calling showSuggestionList on each value change and key up event.
Now, how do I get the suggestbox to automatically choose the first item in the suggestion list?
One of the methods I tried is to programatically simulate key presses, i.e
suggestBox.setFocus(true);
NativeEvent enterEvent = Document.get().createKeyPressEvent(false, false, false, false, KeyCodes.KEY_ENTER);
DomEvent.fireNativeEvent(enterEvent, suggestBox);
textBox.setFocus(true);
This doesn't work at all. The enter key isn't simulated. Another possible solution is to extend SuggestionBox.SuggestionDisplay, but I'm not too sure how to that. Any pointers appreciated.
Update: I'm still working on this and trying various methods.
Here, I tried to implement my own SuggestionDisplay by subclassing DefaultSuggestionDisplay and overriding getCurrentSelection() to make accessible from my class. This doesn't work either. Null is returned.
private class CustomSuggestionDisplay extends DefaultSuggestionDisplay {
#Override
protected Suggestion getCurrentSelection() {
return super.getCurrentSelection();
}
}
suggestBox.setAutoSelectEnabled(true);
textBox.addKeyUpHandler(new KeyUpHandler() {
public void onKeyUp(KeyUpEvent event) {
suggestBox.setValue(textBox.getText(), true);
suggestBox.showSuggestionList();
if (suggestBox.isSuggestionListShowing()) {
String s = ((CustomSuggestionDisplay) suggestBox.getSuggestionDisplay()).getCurrentSelection().getDisplayString();
Window.alert(s);
}
}
});
Here, I tried to attach a value change handler to the SuggestBox, and casting the event type to SuggestOracle.Suggestion. Again, null is returned.
suggestBox.addValueChangeHandler(new ValueChangeHandler<String>() {
public void onValueChange(ValueChangeEvent<String> event) {
String s = ((SuggestOracle.Suggestion) event).getDisplayString();
Window.alert(s);
}
});

Use suggesBox.setAutoSelectEnabled(true)
Here more info about the SuggestBox of GWT:

You could try using addSelectionHandler in conjunction with setAutoSelectEnabled to receive an event whenever a suggestion is selected. You could also have your Oracle send a message when it suggests something, or your Display send a message when it displays a list:
public class AutomaticallySelectingSuggestionDisplay extends SuggestBox.DefaultSuggestionDisplay {
#Override
protected void showSuggestions(SuggestBox box, Collection<? extends SuggestOracle.Suggestion> suggestions, boolean isDisplayHtml, boolean isAutoSelectEnabled, SuggestBox.SuggestionCallback callback) {
super.showSuggestions(box, suggestions, isDisplayHtml, isAutoSelectEnabled, callback);
fireValueChangeEventWithFirstSuggestion(suggestions);
}
}
This idea feels a little muddled to me, so I hope you can find a solution just using event handlers.

Set focus on a component with Apache Wicket?

How do you set focus on a component with Apache Wicket? Searching leads to very little information, mostly on setting the default field. I do not want to set a default field, rather I am looking to set focus when, for example, a specific radio button is selected.

I suggest using the native org.apache.wicket.ajax.AjaxRequestTarget#focusComponent(). For example:
/**
* Sets the focus in the browser to the given component. The markup id must be set. If
* the component is null the focus will not be set to any component.
*
* #param component
* The component to get the focus or null.
*/
org.apache.wicket.ajax.AjaxRequestTarget#focusComponent(Component component)

Once you create your behavior to set the focus, you should be able to add it to the component on any event, just make sure that component is part of the AjaxRequestTarget. I don't see why this wouldn't work...
myRadioButton.add(new AjaxEventBehavior("onchange") {
#Override
protected void onEvent(AjaxRequestTarget target) {
myOtherComponent.add(new DefaultFocusBehavior());
target.addComponent(myForm);
}
});
Here's a link that shows how to create the default focus behavior if you do not have one already:
http://javathoughts.capesugarbird.com/2009/01/wicket-and-default-focus-behavior.html

If you only want to setFocus through javascript and don't want to reload a form or a component, you can use the following code:
import org.apache.wicket.Component;
public class JavascriptUtils {
private JavascriptUtils() {
}
public static String getFocusScript(Component component) {
return "document.getElementById('" + component.getMarkupId() + "').focus();";
}
}
And then in any Ajax Method you can use:
target.appendJavascript(JavascriptUtils.getFocusScript(componentToFocus));

For a pop-up like modalWindow my workaround solution was to use the attribute "autofocus" on the first input tag.
An easy solution is to add it to the html directly.
<input ..... autofocus>
Another solution is to add it to the modalWindow itself:
#Override
public void show(AjaxRequestTarget target) {
super.show(target);
setUpFocus();
}
protected void setUpFocus() {
DeepChildFirstVisitor visitor = new DeepChildFirstVisitor() {
#Override
public void component(Component component, IVisit<Void> iVisit) {
if (isAutofocusable(component)) {
component.add(new AttributeAppender("autofocus", ""));
iVisit.stop();
}
}
#Override
public boolean preCheck(Component component) {
return false;
}
};
this.visitChildren(FormComponent.class, visitor);
}
protected boolean isAutofocusable(Component component) {
if (component instanceof TextArea ||
component instanceof DropDownChoice ||
// component instanceof RadioChoice ||
component instanceof AjaxCheckBox ||
component instanceof AjaxButton ||
component instanceof TextField) {
return true;
}
return false;
}
RadioChoice is commented out because this solution is not working on that. For RadioChoice i would recommend to implement a FocusedRadioChoice:
public class FocusedRadioChoice<T> extends RadioChoice<T> {
//constructors...
#Override
protected IValueMap getAdditionalAttributes(int index, T choice) {
super.getAdditionalAttributes(0, choice);
AttributeMap am = new AttributeMap();
am.put("autofocus", "");
return am;
}
}

Is there a way to achieve the same without JavaScript?
(I am implementing a form with a feedback-Panel that only comes up when Javascript is turned off, so it would not make sense to depend on JavaScript there...,-)
I could only find answers which use JS .focs()... maybe Wicket 1.5 will provide a method Component.setFocus()...

If you happen to be using an Ajax button, you can simply call target.focusComponent(myComponent); in the button's onSubmit method.

#martin-g 's solution was the only solution that got it working for my scenario - a modal/pop up.
Note:
I think autofocus embedded explicitly in HTML only works on page load, not modal load so any efforts to skillfully set the autofocus attribute in the HTML of a modal just fail miserably - always.
Here I lay out the steps for setting the focus on an input field called 'myInput' using the full power of Wicket (no JS!):
In onInitialize:
// Make sure the field has an ID in markup
myInput.setOutoutMarkupId(true);
Provide an overridden show method where you call the focusComponent method:
public void show(AjaxRequestTarget target)
{
// Make sure you call the super method first!
super.show(target);
target.focusComponent(myInput);
}
This does require that your component is an attribute of your modal content class so that you can access it in the show method. To avoid creating a class attribute for your input component you could blend this solution with the solution from BlondCode by replacing that solution's
component.add(new AttributeAppender("autofocus", ""));
with
target.focusComponent(component);
This also works!