1. Link the library project to all relevant projects (“Project Preferences” -> “Java Build Path” -> “Projects” -> “Add…”)
2. Then, add the client-side code of the library (by adding it as a module.) Therefore, edit the gwt.xml of your application and add for example <inherits name="net.svenbuschbeck.gwt.lib.SuperLib "/> where SuperLib is the file name of the gwt.xml file in you library project and before that is the package it lies in.
3. Add the code to the project by linking a source folder. Unfortunately, this is required if you do not want to write an Ant script to compile your application. (If you prefer Ant check this out) I don’t like the idea of using such a script because if you forget to run it each time you make changes, you will end up in confusion—let’s go for the convenient, automatic way then.
   1. Add a folder to your application project; open the “advanced” section in the folder creation dialog, select “Link to alternate location” and pick the source folder (usually “src”) of your library project. (Hint: if you work within a team using a versioning system, you can create a variable for that folder and use this instead. This way, each of your colleagues can put the library project in a different folder and accommodate for that by adjusting the variable )
   2. Right click the folder, “Build Path” -> “Use as Source Folder”. Done.

Surprisingly, the GWT plugin for Eclipse does not honor the project linking, thus all the references need to be made explicit or you will end up with lots of the following: ClassNotFoundException.

I tried to add an addAttachHandler to the RootPanel to get informed about the root panel getting detached from the DOM so that I can finalize my application. Surprisingly, that does not work in Chrome (tested Chrome and Firefox only).

But besides that this sounds like a bug to me, I found the “proper” way of doing things before the application ends:

Window.addWindowClosingHandler(new Window.ClosingHandler() {
	@Override public void onWindowClosing(ClosingEvent event) { ... }
});

In the end, I think something like Document.addUnloadHandler would be more suggestive… closing the window or reloading a page is both exiting the application by unloading the DOM — not closing the window.

My goal was to set a cookie to expire in about one month from today like this:

Date expires = new Date(new Date().getTime() + 1000 * 60 * 60 * 24 * 30);
Cookies.setCookie("myCookie", "myData", expires);

And kept wondering why the cookie never got stored.

And finally created a simple test case like this:

Date today = new Date();
Date tomorrow = new Date(today.getTime() + 1000 * 60 * 60 * 24);
Date nextMonth = new Date(today.getTime() + 1000 * 60 * 60 * 24 * 30);

And got following dates:

today=Mon Feb 07 14:27:50 CET 2011
tomorrow=Tue Feb 08 14:27:50 CET 2011
nextMonth=Tue Jan 18 21:25:02 CET 2011

According to Java’s calculation, the cookie was expired already before even being set.

Took me a bit to understand why:
1000 * 60 * 60 * 24 * 30 = 2,592,000,000 = 0x9A7EC800
Thus, the first bit got set to one… a classical overflow causing the integer value to become negative — just try:

System.out.println(1000 * 60 * 60 * 24 * 30);

It will print out -1702967296.

Fix: Add a little L will solve the issue by forcing the compiler to calculate using the scope of long:

Date nextMonthLong = new Date(today.getTime() + 1000L * 60 * 60 * 24 * 30);

I guess I will fall for that one again sometime as the error is not obvious in my opinion — especially because getTime() returns a long and still, the compiler sticks with an int for the multiplication part.

RootLayoutPanel.get().addDomHandler(new ContextMenuHandler() {

	@Override public void onContextMenu(ContextMenuEvent event) {
		event.preventDefault();
		event.stopPropagation();
	}
}, ContextMenuEvent.getType());

Same should work for RootPanel.

After that, it is possible to make use of the right mouse button for example like this:

someWidget.addDomHandler(new MouseMoveHandler() {

	@Override public void onMouseMove(MouseMoveEvent event) {
		if (event.getNativeButton() == NativeEvent.BUTTON_RIGHT) {
		...

The first part of the list of arguments should look something like that:

-remoteUI "${gwt_remote_ui_server_port}:${unique_id}" -startupUrl GlocalUiPg2.html -logLevel INFO -codeServerPort 9997 -bindAddress 0.0.0.0 -port 8888 ...

Now, you can access you app using the OSX’s public IP address. (You can get to know your IP by having a look at the network preferences panel.) Launching GAE from Eclipse, you will see a different link (URL) in the “Development Mode” tab now, containing the public IP already. Using that one in, say, your Firefox on Mac, it will ask you now whether you want to allow the debugger access. That is also due to the fact, that you are now using a public address, so it is not clear to your local debug server, whether that request came from the same computer or someone else in the network.

class A {}
class B extends A {}

It is just logical that casting B to A works fine:

A anObjectOfClassA = new B();

But when it comes to collections of As and Bs, a strange phenomenon appears in Java:

Collection<B> collectionOfBs = new LinkedList<B>();
Collection<A> collectionOfAs = (Collection<A>)collectionOfBs; // this line does not compile!

That is, though the collection wrapper (the java.util.Collection class) is the same and B extends A, casting a collection of objects of class B to a collection of objects of class A throws an compile-time error.

But it works using generics (the whole class for the sake of completeness and reusability):

import java.util.Collection;
import java.util.LinkedList;

public class CollectionCastingExample {

  class A {}
  class B extends A {}

  Collection<B> collectionOfBs = new LinkedList<B>();
//  Collection<A> collectionOfAs = (Collection<A>)collectionOfBs;

  Collection<A> collectionOfAs = downCastCollection(collectionOfBs, A.class);

  /**
   * Casts a collection of objects of class B where B extends A to a collection of objects of class A.
   *
   * @param <T> Base class
   * @param collection Collection of objects of a class extending T
   * @param aClass Representation of T
   * @return Collection of objects of T casted from given collection of objects of a class extending T.
   */
  @SuppressWarnings("unchecked")
  public static <T> Collection<T> downCastCollection(Collection<? extends T> collection,
      Class<T> aClass) {
    return (Collection<T>) collection;
  }
}

Despite the fact that a @SuppressWarnings("unchecked") is required, it avoids iterating over the whole collection of Bs and casting each of them from B to A plus adding them to a new collection of As.

Check list (some should be replaced with whatever you want to call your new service):

• Copy or create files:
  SomeService.java and SomeServiceAsync.java in client package
  SomeServiceImpl.java in server package + change implementation statement to SomeService
• Adjust web.xml:

  <servlet>
  	<servlet-name>someServlet</servlet-name>
  	<servlet-class>some.package.SomeServiceImpl</servlet-class>
  </servlet>
  <servlet-mapping>
  	<servlet-name>someServlet</servlet-name>
  	<url-pattern>/[copy base directory name from other service declaration]/some</url-pattern>
  </servlet-mapping>

• Annotate interface SomeService.java:

  @RemoteServiceRelativePath("some")

• Connect to your new service in the client:

  private final SomeServiceAsync someService = GWT.create(SomeService.class);

Definitely some possibilities to make a mistakes or miss something here.

But it is not possible to resize system relevant partitions while the system is running — makes sense, right?

But you can download GParted as LiveCD ISO file and burn it on a CD. After that, restart your computer with the CD in your drive and a small linux will start up directly from CD including GParted, thus allowing you to modify any drive and partition there is. Do all required changes, click the exit button and you are done. In my case, the computer did not reboot automatically, instead I ended up with a command line interface — use the command “sudo reboot” to restart the system yourself if that happens.

And just by the way, GParted does also handle Windows partitions easily — so there is no need to buy or “get” Partition Magic from somewhere. But never forget to backup your data first.

Yet another hint: GParted works most reliable if you do one step at a time. So for example, there are partitions A and B (A is in front of B) and you wish to give some of the free space in A to B. You need to do following steps: Shrink A, move B left and finally grow B. From my experience, GParted works best if you really do all those steps separately, apply each of then, and go for the next one if the last one finished successfully.

There was only one problem I ran into and I want to share the solution.

I am running Kubuntu 10.04 (just upgraded today) on a Lenovo IBM ThinkPad R60 (Yes, one of those with both brands on them ) with an ATI Radeon X1400 graphics device. But since upgraded, my display started flickering — not permanently but unbearable.

The solution that worked for me (at least partially — see below — and this is of cause depending on the graphics device type) was to install the proprietary ATI drivers. I know, it is not a good solution, I do not like to use them neither and if anyone out there is reading this with a better solution in mind, let me know it!!
Edit 2011-02-14: Added a new post with an additional, alternative solution here.

So what you need to do is  to get your favorite package management tool (e.g. Synaptic or KPackageKit) — just hit Alt+F2 and type “package” and pick KPackageKit from the list (it will ask you for the super user password). Then, search for “fglrx”. In KPackageKit, you will find a result titled “Video driver for the ATI graphics accelerator”, and something below the title like “fglrx — 2:8.723.1-0ubuntu3” but the version number should not matter. Click the arrow to the right, hit “Apply” and after rebooting, everything should perfectly without any configuration.

Good luck.

Problems noticed so far: The driver causes “Segmentation Fault” error messages, e.g. when trying to open up the display settings. That’s ugly, I know. But you can read in several forum and blog posts, that the support for the former nicely working driver for the ATI X1400 has been discontinued since 10.04, hence, it’s just good luck that the fglrx works somehow — good to know *after* upgrading, right. But still, the flickering was unbearable for me, thus, I accept the issues for now. I will keep my eyes peeled hoping for a proper solution in the future.