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Taking the SCJP

Reading a book on the Sun Certified Java Programmer (SCJP) test is interesting and worthwhile, but the test itself is bogus.
Says who? I do…

I took the SCJP for Java 2 many many years ago and subsequently also passed the SCJD and SCWCD tests. So, I feel I experienced a fair share of the Sun certification universe.

SCJP is known as the “API test” and its successful completion is the basis for all other Sun Java certificates. You’re expected to be familiar with many of the basic Java/OO concepts and APIs – sometimes down to the method signature. As such, passing the test shouldn’t require at lot of studying for any serious Java engineer since this is our daily bread and butter.
So, going through a certification prep book should hopefully not teach you a lot of new stuff (i.e. things you weren’t previously familiar with) but rather fill your know-how gaps. And that’s the interesting part. You might uncover surprising aspects of the JLS (Java Language Specification) which can be valuable.

However, it’s the way questions and code samples are formulated in the test that hamper the significance of its results. The time limit for the full Java 6 test is 210min (yes, that’s 3.5h!) and it consists of 72 questions. While you may finish a lot quicker it certainly is a primary test for your ability to concentrate in a test center. Furthermore, the majority of the questions contain code samples that are outright silly. You’ll see code that no sensible programmer would ever craft like that – even if the JLS allowed it.
You job would then be to find the missing ‘;’, the missing ’static’ modifier, the illegal [] in an array declaration, the overridden instead of overloaded method, the illegal auto-boxing, the… you name it i.e. mainly stuff the compiler would report anyway. Finding the correct answer has become harder over the years because for most questions two of the possible answers nowadays are “Doesn’t compile” or “Fails at runtime”.

So, practicing for the test is not so much about learning Java as it is about getting accustomed to this type of questions and finding a (personal) strategy to tackle them.

All in all, I don’t think a Java test which a good Java developer might still flunk has a lot of significance. And passing this test doesn’t necessarily mean that you’re a good developer, either. Pity.

There’s no such thing as a “static inner class” in Java

It was only recently after many years of Java programming that I found out that there’s no such thing as a “static inner class”. Such classes are called static nested classes.

-> http://www.coderanch.com/t/442837/Programmer-Certification-SCJP/certification/Members-inner-classes

Windows Control Panel applications

List of Windows control panel application and the name of the respective .cpl file in the %systemroot%\system32 folder. Uuuhhhm, you ask how knowing this should help you? Well, in the control panel you can’t simply right-click an application an chose “Run as…” from the context menu – that option is not available. Hence, you need to find the respective .cpl file and repeat that operation there…

Control Panel Applet Icon	.cpl file
Console	console.cpl
Accessibility Options	access.cpl
Add Hardware Wizard	hdwwiz.cpl
Add or Remove Programs	appwiz.cpl
Administrative Tools	Shortcut to main.cpl
Date and Time (Clock)	timedate.cpl
Compaq Insight Agents	cpqmgmt.cpl
Date and Time	timedate.cpl
Display (Properties)	desk.cpl
Fonts	Shortcut to main.cpl
Game Controllers (Joystick)	joy.cpl
International and Regional	intl.cpl
Internet Options	inetcpl.cpl
Infrared Port	irprops.cpl
Keyboard	main.cpl
Licensing	liccpa.cpl
Mail	mlcfg32.cpl
Modem and Phone	modem.cpl
Mouse and Keyboard	main.cpl
Netware Client	nwc.cpl
Network Connections (Connectivity)	ncpa.cpl
ODBC Data Source Administrator	odbccp32.cpl
PC Card	devapps.cpl
Phone and Modem Options	telephon.cpl
Power Options (Management)	powercfg.cpl
Printers and Faxes	Shortcut to \Documents and Settings\ user \Desktop
QuickTime	QuickTime.cpl
RealPlayer Preferences	prefscpl.cpl
Regional and Language Options	intl.cpl
Scanners and Cameras	sticpl.cpl from wiashext.dll
Server Manager	srvmgr.cpl
Scheduled Tasks	Shortcut to main.cpl
Sounds and Audio Devices (Multimedia)	mmsys.cpl
Speech Properties	Shortcut to :\Program Files \Common Files \Microsoft Shared \Speech \sapi.cpl
System	sysdm.cpl
Taskbar and Start Menu	Shortcut to \Documents and Settings\ user \Desktop
Taskbar and Start Menu	access.cpl
TweakUI	tweakui.cpl
User Accounts (Manager)	nusrmgr.cpl
Wild Tangent (spyware)	wtcpl.cpl
Windows Firewall	firewall.cpl

For explanations check: http://en.wikipedia.org/wiki/List_of_Control_Panel_applets_(Windows)

USB printer in Airport Express not showing

A brother printer hooked up to my AirPort Express base station was not recognized by the AirPort – so it seemed.  The respective dialog in the AirPort Utility said: “USB Printer: None”.

I spent quite some time trying to find out what the problem was. It turned out that the dialog simply didn’t tell the truth. The “AirPort” dialog (left most in the menu) did indeed list the printer correctly:

After I found that bug setting up the printer both in OS X and Windows XP was a breeze. In OS X you go to System Preferences -> Printer / Fax -> + sign -> choose “Default” in the top connection-type menu. OS X will then try to locate the printer with Bonjour and populate the add-dialog with proper values. For Windows you need to install Bonjour from the CD that came with your AirPort Express base station.

Tell me when your web site requires cookies – please

I recently started surfing the Internet with cookies disabled in my browser. You wouldn’t believe how many sites that require cookies to be enabled fail to tell me so. I would guess it’s about 90%. Most often I notice this when I try to log in to a site and simply can’t get past the login dialog. Sad if web developers don’t think that far…

I’ve long given up sending a friendly email to the respective webmasters – it’s just too time consuming.

ASUS Pundit P4S8L

I just spent way too much time looking for information for an ASUS P4S8L mainboard built into a Pundit PC. The mainboard is not listed in the proper section on asus.com. I finally figured that in the ‘Product’ category one must not choose ‘Mainboard’ (which would be obvious, right) but ‘Barebone’ instead. Then you need to pick ‘Pundit’ -> ‘Pundit-S’.

To easen this for you I attached the mainboard manual to this post.

GWT widget libraries, a market overview

After many hours searching the Internet for GWT widget libraries, analyzing them, and taking notes I thought I might as well publish my findings here. Feel free to comment and point out inconsistencies.

At the moment the market seems to be split into two segements:
- a few small or medium-size, low-key libraries with little activity
- the whole “Ext” gang

However things change very quickly, in a matter of months, and the end of 2008 saw the advent of a new-kid-on-the-block: SmartGWT.

Small, or medium-sized libraries

• GWT-SL/WL, a collection of server- and client-side tools. No real show case that demonstrates the power of the library is available. Last minor release in December 2008. Little SVN activity over the entire course of 2008.
• GWT Tatami, based on the DOJO JS framework. Show case isn’t impressive, but project is active. Continuous SVN activity. Road map for first half of 2009 available.
• GWTLib, continuous but little SVN activity. Offers hardly anything else but but table-centric widgets.
• GWT Tk, tbd
• Rocket GWT, tbd
• “vanilla” GWT, Google’s on-board GWT widgets. Nothing fancy, but clean and slick.

The “Ext” corner
A long time ago (think Internet time ) a guy called Jack Slocum built an extension to Yahoo’s YUI widget library named YUI-Ext. It evolved and became independent, Ext JS was born and with it a new company: http://extjs.com. The library quickly became very popular.
Once GWT was released people started writing widget libraries for it. Boston-based Sanjiv Jivan started GWT-Ext and based in on Ext JS. Darrell Meyer wrote MyGWT, a pure GWT widget library which shared the Ext JS l&f. It was voted #1 widget library one year ago.
In April 2008 things became very nasty an confusing when Jack Slocum changed the Ext JS license from LGPL to GPL thereby forcing GWT-Ext to stick with Ext JS 2.0.2 which was the last version available under LGPL. Furthermore, he hired Darrell Meyer who brought his MyGWT as a dower into the relationship. As a result, Ext JS published its own GWT widget library called Ext GWT. Now developers had the choice between GWT-Ext (full OSS with LGPL) and Ext GWT with a dual-licensing model. The GWT widget “war” (see references 1-5 below) turned many away from Jack Slocum’s Ext JS because they disliked the way the company treated the GWT community.
On November 26th, 2008, the game changed again when the GWT-Ext crew announced that they would no longer build major new features but instead be migrating to SmartGWT, a library created by GWT-Ext developer Sanjiv Jivan . SmartGWT 1.0 had been announced only two weeks earlier.

[1]http://www.jroller.com/sjivan/entry/my_response_to_jack_slocum
[2]http://pablotron.org/?cid=1556
[3]http://www.gwtsite.com/ext-gwt-gwt-ext-what-now/
[4]http://ajaxian.com/archives/to-gwt-ext-or-to-ext-gwt
[5]http://gwt-ext.com/license/

Wake-On-LAN, WOL, with Apple iPhone Remote

With Apple Remote for iPhone and iPod Touch you control iTunes on a remote computer.

What I only recently found out is that Apple Remote acts as a Wake-On-LAN (WOL) client. At least it does that in my environment. My Mac Mini wakes up from sleep when I start Apple Remote on the iPod Touch and have it try to connect to iTunes on the Mac Mini.

I find this a little odd because none of the articles I found (App Store and apple.com) mention this feature. Of course I’m happy about it nonetheless.

Mac – Windows networking issues

My small home network consists of a Windows XP PC, a MacBook with OS X Leopard, and a Mac Mini with OS X Leopard. Several networking issues kept bugging me:

1. the XP PC sees the Mac Mini in the network neighborhood but can’t access its shares, mapping those shares only works if the Mac Mini is addressed by its name instead of its name
2. the XP PC doesn’t see the MacBook at all, neither by name nor by IP
3. both Macs can list the PCs shares, but connecting to them results in the errors “no direct map for 32 bit server error (0xc0000205)” and “broken pipe” in the OS X console
4. both Macs cannot connect to the PC using its name, but only by using <name>.local

The first issue was solved by updating the Mac Mini (and the MacBook for that matter) to the latest Leopard version 10.5.6. However, this didn’t help with any of the other issues.

Issue number 3 was solved with the help of a geekstogo.com article. In the XP registry I needed to add the IRPStackSize parameter to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters and set its value to 18 (decimal) according to this Microsoft KB article: http://support.microsoft.com/kb/285089.

Issue number 2 was related to a fu… up “WINS” configuration on the MacBook. When I checked whether the workgroup name in the WINS tab in System Preferences -> Network -> Advanced was set correctly it was empty. So, I tried to enter the same name as on the PC and on the Mac Mini, but the change would never get persisted i.e. remembered. I did as adviced in http://discussions.apple.com/thread.jspa?messageID=6198136 and now the MacBook appears correctly in the XP network neighborhood. However, its shares still could not be accessed. So, I checked System Preferences -> Firewall and realized that I had checked ‘Allow only essential services’ instead of ‘Set access for specific services and applications’. Issue 2 solved.

At this point I discovered the great article ‘Explanation of Leopard NetBIOS (Windows Sharing) Wackyness With Solutions’. It’s got extensive explanations and good tips.

And…while reading it, time passed…more time passed…and all of a sudden my XP system showed up in the Finder with its real name i.e. there was no need to address it with <name>.local. Issue 4 solved.