GWT Error Message “Asked for attribute parser of no type”

Example:

public boolean isCollapsed() {
	return panel.isVisible();
}

public void setCollapsed() {
	panel.setVisible(false);
}

Seen it? Despite the complicated and cryptic error message, the mistake is rather simple: the setter method is missing a parameter, i.e. “public void setCollapsed(boolean collapsed) {“.

Uploading File to Server: Access Denied

Simple task: upload a file to the server. Achieved so far: upload form works and the file gets transferred to the server.
But as soon as the file is written, I get one of that:
“java.security.AccessControlException: access denied (java.io.FilePermission /some/folder/upload__71c20601_12b1b66bc39__7ffa_00000000.tmp write)”
I am amazed how much searching is required to find some information about how to modify the file permissions for the local app engine! And in the end, it turns out that there is an issue with the GAE on Mac but without a way to configure the local Jetty server to allow write access.
As soon as I deploy the app to a Tomcat on Linux, it works like a charm!

GWT Does Not Load Module in Local AppEngine

The issue arose after I renamed the module file (ending with .gwt.xml) to better represent the module functionality. I also updated all relevant files in the project (search for files containing the old name to find them) accordingly.

Starting the application after that modifications ended up in an error (“[ERROR] Unable to find ‘<old module name>.gwt.xml’ on your classpath; could be a typo, or maybe you forgot to include a classpath entry for source?”) as the AppEngine tried loading the module by its old name.

Solution: Delete the launch profile for the project (by choosing “Run As…” -> “Run Configurations…” from the context menu).

Obviously the GWT does not check nor update the automatically generated launch profile thus you need to delete it to force the GWT to create a new profile from scratch taking the project changes into account. You might also adjust the profile according to the changes made, but deleting it is the safe and easy way.

Flickering Screen After Upgrade to Kubuntu 10.04

First of all, I was amazed how smoothly the upgrade went. (K)Ubuntu and I guess other distributions as well have gone quite a far way to become platforms for everybody — with a lot of software but even more tools, helpers and automatic background services — like the nice upgrade service.

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.