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Unreachable catch block

Always contruct try-catch blocks in a way that assumes catching Exceptions from more detailed to more generic.

Example

try {
    String [] tab = null;
    System.out.println(tab[3]);
} catch (Exception e) {
    System.out.println("Exception");
} catch (NullPointerException e) {
    System.out.println("NullPointerException");
}

The above presented snippet will cause compilation error:

Unreachable catch block for NullPointerException. It is already handled by the catch block

Sun Certified Java Programmer

Okay, I’ve been working with Java for a few years now, starting from academia and ending with business solutions. So yeah, I think I can say I know Java and some of those technologies like J2SE, J2EE or J2ME, with their own standards and solutions. Therefore, I’ve decided I’d take Sun Certified Java Programmer (SCJP) in a few months.

If …

Create a report with Reporting Services

If you want to create a report in 5 mins, you should follow this tutorial.

All requirement software can be found there. I installed the following:

The tutorial instructs you how to create the report (RDL file): how to define the data source, layout and how to preview the report.

Once you’re done, you can use Report Manager to deploy …

Parser Error Message: This page allows a limit of 200 controls, and that limit has been exceeded.

By default, web.config of SharePoint (should be there: C:InetpubwwwrootwssVirtualDirectories80) defines the maximum number of controls as 200. Should you define more on a page you’ll probably get an error similar to this:

spscreen

Solution

In order to fix it, edit this web.config. Find configurationSharePointSafeMode tag and change the MaxControls attribute to a bigger number. Once you do this, reload the …

Is it possible to fail a load test?

It’s not really possible to fail a load test because by default it always ends with status ‘Completed’. Because of that anytime a load test completes one musts analyze the results – if performance stayed at the acceptable level. So, despite being a powerful tool, load tests require human attention, which makes the whole testing process less automate.

Luckily, load …

What if you extend an abstract class and implement an interface when both define a method with the same name?

Imagine you need to implement a class that extends an abstract class and implements an interface when both define a method with the same name – test().

Example

interface Implementable { public void test(); }
abstract class Superclass { public abstract void test(); }

public class Test extends Superclass implements Implementable {
    /* definition of load method(s)..... */
}

The …

Ireland again

Greetings from Ireland!

It’s the second time I went to Galway, Ireland. Again the Green Island welcommed us with rain…
Again, I work as a researcher, Java programmer in Digital Enterprise Research Institute (DERI), Galway, Ireland. The main topic of my research is how to adopt Social Semantic Information Sources (SSIS) to e-Learning. Actually, this is the title of my …

Exeptions and Errors in Java

In the diagram below I present the hierarchy of most common Exceptions and Errors:


Object
 |
 |_ Throwable
    |
    |_ Error
    |   |
    |   |_ AssertionError
    |   |
    |   |_ LinkageError
    |   |   |
    |   |   |_ ExceptionInInitializerError
    |   |   |
    |   |   |_ NoClassDefFoundError
    |   |   |
    |   |_ VirtualMachineError
    |       |
    |       |_ StackOverflowError
    |
    |_ Exception
        |
        

Test your Java experience for free – JavaBlackBelt

Recently I’ve come across another very interesting social service – JavaBlackBelt. Basically it gathers programmers who use Java language and related frameworks and aspects (OO programming, JSP, Struts, JSF, EJB). There are even exams on C#, Ruby, JavaScript, and AJAX but some of them are still beta versions.

Of course I’ve taken a couple of exams and this is my …

IKHarvester

Some time ago I wrote about Didaskon, a framework for composing curriculum for a specific user, basing on his profile and using formal and informal knowledge. I belong to team of the developers.

At the moment, I am developing the one of its component – IKHarvester (Informal Knowledge Harvester). It aims at collecting (harvesting) data from Social Semantic Information Sources …