Monday, March 31, 2014

could not find or load main class [java]

If you got this error "could not find or load main class" trying to execute your freshly compiled java program you have a problem with your classpath variable that doesn't include your current folder.

Open the Control Panel -> System -> Advanced System Settings -> Advanced [table] -> environment variables and then "edit" your CLASSPATH adding a dot "." at the end.

You have to re-open your Windows console to make the change active.

From the Oracle documentation
"The default class path is the current directory. Setting the CLASSPATH variable or using the -classpath command-line option overrides that default, so if you want to include the current directory in the search path, you must include "." in the new settings."

Monday, March 24, 2014

Oracle Database 11g R2: installation hangs [on Windows]!

You are on Windows and Your oracle 11g installation freezes/blocks/stops after the requirements page?

Probably there is an easy solution:

log in as administrator. Even if you tried to install the oracle database11g as a user with admin rights, this is not enough! You have to log in as Amistrator, then it works (probably)!

Oracle 11g R2 client install. hangs on step 5 of 7 in VM with Win. 2008 R2

Friday, March 14, 2014

ASCII, UNICODE, UTF-8, UTF-16, ... character set, encoding ecc

Here I found THE resource on the subjects: character set and encoding.
It's a small and effective guide to the mysterious world of character sets, encodings, Unicode, all that stuff.

Wednesday, March 12, 2014

How to remove Oracle DB 11 and 12 in Windows

  • Uninstall all Oracle components using command line uninstaller located at ORACLE_HOME\deinstall\deinstall
  • Run regedit.exe and delete the HKEY_LOCAL_MACHINE/SOFTWARE/ORACLE key. This contains registry entires for all Oracle products.
  • Delete any references to Oracle services left behind in the following part of the registry: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Ora* It should be pretty obvious which ones relate to Oracle.
  • Reboot your machine.
  • Delete the "C:\Oracle" directory, or whatever directory is your ORACLE_BASE.
  • Delete the "C:\Program Files\Oracle" directory.
  • Empty the contents of your "C:\temp" directory.
  • Empty your recycle bin.

Monday, March 10, 2014

Fundamentals of Mercurial: the version control software

This two are the most important references to Mercurial, the easy to setup version control system
This tutorial will explain you the fundamental ideas. Just pay attention that
hg commit -m "MESSAGGE"-u USERNAME

A lot of resources are available here!

This is the workflow, to use when working with other people (from
  1. If you haven’t done so in a while, get the latest version that everyone else is working off of:
    • hg pull
    • hg up
  2. Make some changes
  3. Commit them (locally)
  4. Repeat steps 2-3 until you’ve got some nice code that you’re willing to inflict on everyone else
  5. When you’re ready to share:
    • hg pull to get everyone else’s changes (if there are any)
    • hg merge to merge them into yours
    • test! to make sure the merge didn’t screw anything up
    • hg commit (the merge)
    • hg push