Eclipse Losing Reference to JARs

I have this weird problem that every once in a while (especially upon checking in files to SVN/CVS but not limited to that situation) Eclipse will lose reference to class path JARs and start signalling errors everywhere in the code.
What I temporarily did to fix this was to remove a library directory from the [Project] Properties --> Java Build Path --> Source list of a project, save the properties, open them again and add it back in. Problem gone... for a while.

Now I'm trying something I read somewhere: start Eclipse with the -clean command line parameter.

I'll keep you posted...

Feb 2010 Update: with the current version of Eclipse I'm using (Eclipse Java EE IDE for Web Developers, Build id: 20100218-1602) this issue seems to be vanished.

Booting Debian in Text Mode

# disabling login GUI (if not gdm replace with yours)
> update-rc.d -f gdm remove

# re-enabling
> update-rc.d -f gdm defaults

No Javadoc When Hovering Cursor Over Text in Eclipse

I had this weird problem that no javadoc preview showed up when hovering the cursor over java code in Eclipse.

Eclipse version: eclipse-java-ganymede-SR2-linux-gtk
OS: Linux (Fedora 11)

I didn't find out why it didn't work but I found out that it was specific to the version of Eclipse I was using.
When I upgraded to Eclipse Galileo (eclipse-java-galileo-linux-gtk), with exactly the same configuration files and preferences, it worked straight away.

I guess it was a bug of the Ganymede SR2 then...

Unable to Start Eclipse On An Empty Workspace

OS: Fedora 11
Eclipse Version: 3.4.2, Build id: M20090211-1700

If I try to initialize a new workspace (empty but with an existing directory), Eclipse will open as an empty non-killable window.

I was able to have a "dirty" initialization copying the .metadata directory of another workspace I had previously and mysteriously created to the new workspace.

I need to experiment a bit more to see if it's possible to, for example, just create the .metadata directory...

rpmdb: PANIC: fatal region error detected

I had the following error when trying any yum operation on Fedora 11:

> yum update
Loaded plugins: refresh-packagekit
rpmdb: PANIC: fatal region error detected; run recovery
error: db4 error(-30974) from dbenv->open: DB_RUNRECOVERY: Fatal error, run database recovery
error: cannot open Packages index using db3 - (-30974)
error: cannot open Packages database in /var/lib/rpm
Traceback (most recent call last):
File "/usr/bin/yum", line 29, in
yummain.user_main(sys.argv[1:], exit_code=True)
[...]

The googled ;-) solution that worked for me was:

> cd /var/lib/rpm
> rm -f __db.00*
> db_verify Packages
> rpm --rebuilddb

Eclipse: Could not launch the product...

Eclipse crashed or in my case took too long to open a file and I had to shut it down in a not clean state (really surprised it didn't crash during my attempt AND I didn't have to kill it! Great job people@eclipse!).
Next thing that happens when I try to re-launch it using the same workspace is an error message:

Could not launch the product because the associated workspace is currently in use by another Eclipse application

You need to:

1. go to the workspace home directory
2. enter the .metadata directory
3. remove file .lock

and you can happily restart from where you left your job.

JUnit, log4j And Eclipse

If you want Eclipse to pick up your log4j configuration file when you run JUnit tests from within Eclipse you can:

1. Right-click on a test class.
2. Select Run as --> Run configurations...
3. Select the Classpath tab
4. Select the home directory of you project and Advanced
5. Then Add folder and add the folder with the configuration file and you're done.

This will configure the test file's JUnit run options.

If you want to configure all test classes with the same optoins... uhmm... stay tuned. I'll be back.

Fedora 10: Firefox Starts up in Offline Mode

The problem: upon strting Firefox it goes in offline mode even if the network is enabled and working. It's really unconvenient to un-check Work offline from the File menu every time especially if you start up many windows and tabs.
The quick solution is to stop and disable the Network manager application from the System --> Administration --> Services window.
Unless you need it... in that case I can't help you right now...

gedit Color Schemes

If you upgrade to Fedora 10 right now, the new version of gedit doesn't explicitly allow you to set up a custom color scheme. They say in the future there will be an editor for that.
In the meantime what you can do is:

1. > cd /usr/share/gtksourceview-2.0/styles/
2. Copy one of the available schemes to a new one and edit that file to suit your needs.
3. Once you restart gedit, the new color scheme will be available under Edit -> Preferences -> Font & Colors
   

Adding a Script to The Gimp (Linux/UNIX)

1. Create an *.scm file with the script. To create a script you can follow this tutorial.
2. It's recommended to keep them (scripts) in your personal settings. Enter your own gimp directory: ~/.gimp-2.6 or similar, the scripts sub-directory and copy the file there.
3. The place in the menus it will be placed is set in the following command (usually a the end of the script): (script-fu-menu-register "script-fu-photo-scriptName" "/Script-Fu/Photo/"). This will place the script in the Script-Fu --> Photo menu.
4. Then you need to run Filters --> Script-Fu --> Refresh Scripts command.