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How to render LocalDateRenderer for Grid in Vaadin 8

I understand that Vaadin 8.1.0 will include a new LocalDateRenderer to work with Java 8's new date LocalDate but in the meantime I'm trying to setup my own custom LocalDateRenderer. I've got it mostly working in that it's all hooked up but based on the documentation I need to setup an AbstractRendererConnector but there's no such class...
The following code is all in my main UI class (for testing purposes):
private void setupGrid(Grid<Dog> grid)
{
grid.addColumn(dog -> dog.getBirthday(), new LocalDateRenderer()).setCaption("Birthday");
}
class LocalDateRenderer extends AbstractRenderer<Object, LocalDate>
{
public LocalDateRenderer()
{
super(LocalDate.class, "");
}
#Override
public JsonValue encode(LocalDate localDate)
{
return encode(DateTimeFormatter.ofPattern("MMM dd, YYYY").format(localDate), String.class);
}
}
I have confirmed that the LocalDateRenderer is called by adding logging statements, however on the grid no values are displayed. If I use the same code but instead of LocalDate I do it for a Long but instead of extends AbstractRenderer I extend NumberRenderer with my own code then it works.
This lead me to the documentation where I need to setup the Renderer with a AbstractRendererConnector but whenever I try to do this I get the compiler error saying that AbstractRendererConnector cannot be resolved to a type. And then of course I have a number of compiler errors (in the code below). My code for this (still in the main UI class) is:
#Connect(LocalDateRenderer.class)
class LocalDateRendererConnector extends AbstractRendererConnector<LocalDate>
{
#Override
public LocalDateRenderer getRenderer()
{
return (LocalDateRenderer) super.getRenderer();
}
}
Any assistance with how to get it linked up so that it displays my actual dates would be greatly appreciated. Thank you.
Also in the documentation it's not clear which class is which when they refer to TextRenderer since they use the same name to to be different things...

If your compiler can't resolve AbstractRendererConnector<T> to a type, you must be missing a dependency. If you are using Maven, you can add the following dependency, assuming that you have the vaadin-bom in your <dependencyManagement> section.
<dependency>
<groupId>com.vaadin</groupId>
<artifactId>vaadin-client</artifactId>
</dependency>
This artifact is not included by default in most of the Vaadin archtetypes.
Also be careful: there are two Renderer interfaces, one in com.vaadin.client.renderers and one in com.vaadin.ui.renderers. Your covariant return in LocalDateRendererConnector.getRenderer() won't work because AbstractRendererConnector<T> implements a different Renderer interface.

Implementint View.isInEditMode()

I forked Apollo recently from CyanogenMod project for experimenting, this app uses custom views for theming mainly. I am usung AndroidStudio an this IDE requires custom views to implement View.isInEditMode() method to bypass context loading when editing layout.
So I have something like this:
public class CustomButton extends ImageButton
implements OnClickListener, OnLongClickListener {
private final SomeUtililtyClass mResources;
public CustomButton(final Context context, final AttributeSet attrs) {
super(context, attrs);
// Handle editing layout from IDE
if(!isInEditMode()) {
mResources = new SomeUtililtyClass(context);
// do more stuff
}
// some methods
}
Problem is that i have some methods that use mResources that is not always initialized giving me a Java compiler error.
There is an standard way to handle this or should I initialize mResources to null or an empty object?
It is necesary to remove the final modificator?

There's not really a standard way or tricks, it's up to you.
View.isInEditMode() returns true when your class is instantiated under the IDE (the class is really executed), so it's a run-time method rather than a compiler-known value.
In the case you propose, initializing to null and removing final would do it, seems simple. Or maybe,if you want to keep the final keyword, you can pass a NULL context tho the SomeUtilityClass constructor if isInEditMode() and make it just return without executing the conflicting operation.
In my experience, normally doing in the first line of the constructor
if (isInEditMode()) return;
is enough for most classes. But if your class does custom drawing (onDraw / draw / dispatchDraw) you'd need to check it there as well.
At the moment it looks like Eclipse doesn't process click handlers, but this can change in the future.

GWT app UI wont display

I have implemented a simple GWT app that uses 1 Place and 1 Activity (which I have implemented as a Presenter which extends an AbstractActivity and which contains a Composite "view" subclass). The 1 and only UI object in the view is a GWT-Bootstrap NavBar that I want presented at the very top of my "home page".
I'm running the app locally from inside Eclipse and am not getting any compiler or runtime errors. When I go to the URL that the Development Mode console points me to, I get a slight pause in the browser (I assume this is the browser "downloading" the JavaScript) and then I see a blank white screen (instead of my NavBar). The window title is correct (I set this in the module's HTML page) and when I view source I see the same HTML source, so I know that the app's JavaScript is getting to the browser properly. It's just not rendering the NavBar.
I have sprinkled System.out.println() statements throughout onModuleLoad(), my default ActivityManager, ActivityMapper, PlaceHistoryMapper, presenter and view Composite, and all these sysout statements print in the dev console; telling me that I have wired everything together correctly, and that at runtime when the PlaceHistoryHandler#handleCurrentHistory method is called (from inside onModuleLoad), I should be seeing my NavBar.
The only possibilities I can think of are:
I have configured gwt-bootstrap incorrectly; or
I'm not using UiBinder correctly
Something else is wrong with how I am using Activities and Places, or perhaps how I am attaching the UI to RootLayoutPanel inside onModuleLoad().
As for gwt-bootstrap:
I placed the JAR on my project's classpath (I know this because when I include a new UiField of type NavBar inside my widget/view, I don't get any compiler errors)
I added <inherits name="com.github.gwtbootstrap.Bootstrap"/> to my GWT module XML
So if there's anything else I have to configure, please let me know!
As for the UiBinder stuff, here's my widget/view:
public class WebRootDisplay extends BaseDisplay {
private static WebRootDisplayUiBinder uiBinder = GWT
.create(WebRootDisplayUiBinder.class);
interface WebRootDisplayUiBinder extends UiBinder<Widget, WebRootDisplay> {
}
#UiField
Navbar navBar;
public WebRootDisplay(EventBus eventBus) {
super(eventBus);
System.out.println("I get this printing to the console at runtime.");
initWidget(uiBinder.createAndBindUi(this));
System.out.println("...and this too!");
}
}
<!DOCTYPE ui:UiBinder SYSTEM "http://dl.google.com/gwt/DTD/xhtml.ent">
<ui:UiBinder xmlns:ui="urn:ui:com.google.gwt.uibinder"
xmlns:g="urn:import:com.google.gwt.user.client.ui"
xmlns:b="urn:import:com.github.gwtbootstrap.client.ui">
<g:HTMLPanel>
<b:Navbar ui:field="navBar">
<b:Nav>
<b:NavLink href="http://www.google.com">
Home
</b:NavLink>
</b:Nav>
</b:Navbar>
</g:HTMLPanel>
</ui:UiBinder>
One thing I noticed is that I've got my NavBar inside an HTMLPanel in the UiBinder XML. I did this because I used the Google-Eclipse plugin to generate a new UiBinder for me (which autogenerated both the Composite (which I then modified to extend BaseDisplay, which itself extends Composite) as well as the UiBinder snippet. I figured GWT wants me to put all the UI fields inside this HTMLPanel...(?)
If I'm missing anything here please let me know. I'm not instantiating the NavBar field because I believe that's what createAndBindUi does for me.
If both my gwt-bootstrap config and my use of UiBinder looks correct, then something else is obviously wrong and I will have to post more code. I just wanted to hold off on that initially before these first two items were ruled out. Thanks in advance!
Update
Here is onModuleLoad:
public void onModuleLoad() {
// Some homegrown DI stuff. I have verified that the injector works properly.
ApplicationScope appScope = new ApplicationScope();
setInjector(new ApplicationInjector(appScope,
InjectorProvider.newMasterProvider()));
// Add the sole composite child to the RootLayoutPanel.
// I have verified that injectWebRootDisplay returns a fully configured
// WebRootDisplay instance.
RootLayoutPanel.get().add(injector.injectWebRootDisplay());
historyHandler.register(placeController, eventBus, defaultPlace);
historyHandler.handleCurrentHistory();
}

Could you paste the onModuleLoad() part of your code please?
If you don't got any Exception and error message, I think you should check that you add the view properly to the RootPanel, or when you run the app you should check that the view is there in a div in the HTML and just unvisible or something similar.
The UiBinder part looks fine in a first look.
EDIT:
This onModuleLoad() doesn't said too much to me, but you could try something.
I always use the RootLayoutPanel.get() method in the following way:
RootLayoutPanel.get("someDivId").add(injector.injectWebRootDisplay());
So I always add a div or table to the placeholder HTML with a id, so you can refer to that div when you get the RootPanel. I'm not confident about this is necessary, but I saw this at the first time, and it's working properly.
If you have question or problem, please let me know. :)

Well, I've tried a local example looking exactly like yours code, and I think that problem is not in UI binder. The code you provided so far, is correct, so it most likely that the error is somewhere else.
The biggest suspect is the BaseDisplay class. As far as I can see, this class is not from GWT or gwt-bootstrap. You can really quickly check it, by changing WebRootDisplay class, so it extends classic GWT Composite class instead of BaseDisplay (and disabling all mvp stuff for while). If it works, you have a proof that the problem is caused by 'BaseDisplay'
Since I don't have the full code, I can only assume that WebRootDisplay is used also for displaying the views, and most likely the error is that when view is added to that class, previously added widget (in your case it is a NavBar which you add in constructor of WebRootDisplay) is removed. Most likely the problem should be in methods setWidget and initWidget

In my experience with GWT Activities and Places, a common culprit of a blank white page is failing to register the Place's Tokenizer with the PlaceHistoryMapper as so:
/**
* PlaceHistoryMapper interface is used to attach all places which the
* PlaceHistoryHandler should be aware of. This is done via the #WithTokenizers
* annotation or by extending PlaceHistoryMapperWithFactory and creating a
* separate TokenizerFactory.
*/
#WithTokenizers({
MyPlace.Tokenizer.class,
SomeOtherPlace.Tokenizer.class})
public interface AppPlaceHistoryMapper extends PlaceHistoryMapper {}
See https://developers.google.com/web-toolkit/doc/latest/DevGuideMvpActivitiesAndPlaces#PlaceHistoryMapper
Another cause for a white page (particularly when using RootLayoutPanel.get() with a single place is failing to map the place correctly in the ActivityMapper:
/**
* AppActivityMapper associates each Place with its corresponding
* {#link Activity}
*
* #param clientFactory
* Factory to be passed to activities
*/
public class AppActivityMapper implements ActivityMapper {
private ClientFactory clientFactory;
public AppActivityMapper(ClientFactory clientFactory) {
super();
this.clientFactory = clientFactory;
}
#Override
public Activity getActivity(Place place) {
if (place instanceof MyPlace)
return new MyActivity((MyPlace) place, clientFactory);
else if (place instanceof SomeOtherPlace)
return new SomeOtherActivity((SomeOtherPlace) place, clientFactory);
return null; // If your return null with single place bound to RootLayoutPanel
// you may get a blank white page
}
}
See https://developers.google.com/web-toolkit/doc/latest/DevGuideMvpActivitiesAndPlaces#ActivityMapper
Without a more complete code sample it is impossible to determine exactly what is happening, but the two causes outlined above are common oversights which may help anyone who comes across this thread.

Instead of System.println use GWT.log messages. Then open the Javascript console (of Firebug or Chrome) and see where your code ends up. GWT.log will print out in the browser console, so you can see what the compiled JS code does.
Also, if you compile with the Pretty mode, you'll see the generated Javascript code in the browser and be able to step through and see what is being called (or not).

WindowBuilder design-mode not showing up visual characteristics of my Widget

I've implemented my own widget (extending Canvas), that has as distinct characteristic the fact that it's all black.
When adding my canvas to a Shell in design-mode in WindowBuilder, it looks just like a regular canvas, although when in execution-mode everything shows up just alright.
Is there anything I'm missing, or is this an inherent limitation on the part of WindowBuilder?
Here's the code I'm using, just in case:
public class MyCanvas extends Canvas {
public MyCanvas(Composite parent, int style) {
super(parent, style);
setBackground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
addPaintListener(new PaintListenerEx());
}
private class PaintListenerEx implements PaintListener {
#Override
public void paintControl(PaintEvent e) {
e.gc.fillRectangle(MyCanvas.this.getBounds());
e.gc.dispose();
}
}
}

I believe that WindowBuilder is not calling the constructor you are trying to use to initilize your Canvas. WindowBuilder uses some known entry points per framework (like SWT) but sometimes it fails to find one even if you are using the right signature.
If you want to specify an entry point for WindowBuilder you can use this:
/**
* #wbp.parser.entryPoint
*/
to make WindowBuilder start from there but it is not guaranteed to work.

There's also the case where you need to specify the default constructor of a specific graphic element.
/**
* #wbp.parser.constructor
*/
In my particular case entryPoint didn't work and this was the solution.

"Component cannot be instantiated" in Netbeans 7.0.1

EDIT: Sorry, I just started programming in Java. It turned out to be a problem with an out of range array access... I am used to error messages about this kind of thing being automatic...
(using Netbeans 7.0.1)
I have been customizing JTextArea and JTable. I do so by adding a new Java class to my project and then declaring it extends the particular class I want (in my case, either JTextArea or JTable).
I had been using it normally, adding these new classes to JDialogs and JInternalFrames without any problem. I do so by just dragging it to my JDialog or JInternalFrame...
But recently, for some reason, I started getting this error messages "Component cannot be instantiated. Please make sure it is a JavaBeans component."
The JInternalFrames that were accepting the old customized classes still accepts them. But if I try to add the new customized class, it gives me that error message and, afterwards, it starts showing the same message to the old customized classes too...
Something really weird is going on. I copied the same code of a (previously) customized class to a new class (changing the name of the class, of course). Then I try to add this to my JInternalFrame. It gives me the error message! If, before this, I try to add the same customized class (with the original name), it adds the class normally....
This is annoying and I can't solve it. Can anyone help me please?

Thanks a lot for this answer but, if you want to know the reason here you are.
Typically this appears on two position:
an overridden method on your component.
a normal method on your component.
For example:
package UI.Components;
public class LabelComponent extends javax.swing.JLabel {
private javax.swing.JLabel label;
public TextFieldComponent() {
label = new javax.swing.JLabel(_label);
add(label);
}
#Override
public void setText(String text) {
label.setText(text);
}
}
The method setText(String text) is called say in the supper class constructor then it the overridden new method would be called in the case of the (label) variable which is used on this method still no being initialized so a java.lang.NullPointerException will be thowed.
solution:
1) try ... catch:
#Override
public void setText(String text) {
try {
label.setText(text);
} catch (Exception e) {
}
}
2) check:
use null initialization on declaration
private javax.swing.JLabel label = null;
then check on the method
#Override
public void setText(String text) {
if(label != null)
label.setText(text);
}
3)use initialization on declaration:
private javax.swing.JLabel label = label = new javax.swing.JLabel();
and then use setText method in your constructor
label.setText(_label);
note:
in the case of reason (2) a normal method on your component, it is the same as (1) but you may call the method before initialize the variable or assign null to the variable before calling the method and so on and it can being solved by the same ways.

I too faced the same problem, after some search in the web I found the solution for this problem. I don't have a deep understanding of why and how this problem occurs, but I can share with you the solution I found.
When you get such error msg, goto the menu View-->IDE Log or you can open the log from windows_user_Home\.netbeans\7.0\var\log
In that log you have to locate the error msg you got, for example,
INFO [org.netbeans.modules.form.BeanSupport]: Cannot create default instance of: test.Application1
java.lang.NullPointerException
at test.Application1.initLabel(Application1.java:906)
So the problem is in line 906 of your .java file. Open that file and comment those lines and then you will able to overcome the problem.
You can add the component to the Form or jInternalFrame or ...
After adding the component, you can again uncomment those lines. Just Clean and Build your project.
Hope this helps..
Goodluck
reachSDK

I have encountered the similar problem, however in different context.
I have two separate projects, a swing built user interface, and another one that poses as class library.
I added a class to the class library, headed over to the user interface, and implemented this newly added class from the library into the swing interface project in shape of an existing custom JFrame. So what happened to me now that the class loader of course could not find the class because the library project required compiling. The issue was fixed by compiling it.