I deeply impressed how is theserverside.com forum community is weak. I always considered this Java server-side portal as a major resource in this field, but now I am disappointed. I posted a simple question to one of the forums, and it is still unanswered. What’s more it is still the first in the message tree. So, nobody from hundreds of thousands of used didn’t post anything during the whole day. It’s a pity. However there lots of useful stuff like overviews and Tech Talks.

Yesterday night Kiev’s Java community was enjoying a great atmosphere which was established at the most fashionable place I’d never visited before – Orangerea Club (the penthouse part of the Mandarin Plasa center). EPAM Systems held BEA Forum with Peter Cooper-Ellis, executive vice president of the WebLogic Server Business Unit, as a guest star.

The event began a little bit after 7 p.m. and programmers could leave their work places without any hurry. I mean the programmers whose working day is 6am – 9pm like me. I came there right in time. At the entrance I was disappointed when I was asked by security guards to show my clothes in my bag. I don’t like such rudeness at all. And I think that their actions are not allowed by our Law. Their faces were showing that my disapproval didn’t care them at all. Ok, I swallowed it and quickly jumped into an elevator. While I was increasing distance from the ground, a gorgeous downtown scenery of tall, colorful buildings mixed with charming old houses was being revealed to my eyes. Before I was at the highest floor, I’d managed a brief conversation with another Java addicted person who I’d never seen before. We went upstairs a few floors more through dark chill out zone, and eventually discovered light and friendly looking white-colored large room with wide windows instead of walls. In other words we were at the penthouse. The sun was setting and Kiev was perfect.

I registered for conference and got a few useful sheets with related information and two vouchers that could be used for drinking beer and wine. Firstly, I found my co-worker which had already been there for 10 minutes to share my idea that Java rocks today We got a beer and continue socializing with our friends from university, and previous works. Unfortunately I don’t know the major part of the community, therefore I felt a little bit lonely there. It seemed to me that everybody had a great fun talking to each other and sipping juices. They’re laughing and enjoying themselves. As a background sound entertainment was playing a well known rock band “Nochnoy Kvartal”.

When visitors became hot enough, the main part started. After brief introduction of the EPAM representer, Peter started his speech. The presentation was mainly dedicated to the WebLogic application server. Peter mentioned that he had been with this server from the early beginning when BEA bought WebLogic company. As I’m not familiar with WebLogic I just listened carefully him and looking at slides shown at a wide-diagonal plasma monitor. Slides described the key points of the latest version of the cutting edge BEA product. I’m not going to describe here more particular aspects of presentation because as I understood he promised to upload it to the Internet.

After presentation he passionately was giving answers on developers questions. The audience showed deep interest in the main topic. I wanted to ask a question about clustering abilities of the considered application server, but shyness prevented me from that. I hesitated to do it for a few minutes and decided to ask Peter when he was alone. But it didn’t happen because of crowd of programmers who was discussing with him something. Ok, Peter, I’ll ask you next time.

As the last part of performance they organized a lottery with big range of valuable gifts. In spite of the fact that I didn’t win any one of them, it brings me lots of emotions, and I’m really happy that I stayed there and hadn’t left before.

I think that such events could form stronger Java community here that we actually have. What I noticed not depending on the event was people behavior. In comparison with previous gathering I saw a more mature Java community. Nowadays, Java developers in Kiev are not visiting such events only for eagerly seeking job but rather for relax and for fun. I figure out that it is a great sign, and I hope that one day we will host something like JavaOne

Java Rocks!!!

If you are tired of coping with errors like:

• DBCP problem “Name jdbc is not bound in this Context”,
• Cannot create JDBC driver of class ” for connect URL ‘null’,

take a few deep breaths, relax and check out this information:
The most probable cause of your problems is misconfiguring Resource section when you tried to bind a connection pool as JNDI resource. To improve this situations, you might find proper solution using this steps:

• Check whether you’ve installed Tomcat 5.5. If you have, be aware that resource configuration in 5.5 version has changed. Here is an example of META-INF/context.xml file:
  [code lang="xml"]
  

  auth="Container"
  type="javax.sql.DataSource"
  driverClassName="oracle.jdbc.OracleDriver"
  factory="org.apache.tomcat.dbcp.dbcp.BasicDataSourceFactory"
  url="jdbc:oracle:thin:@127.0.0.1:1522:ORADB"
  username="scott"
  password="tiger"
  maxActive="150"
  maxIdle="30"
  maxWait="10000"
  removeAbandoned="true"
  validationQuery="select dummy from dual"
  />
  
  [/code]

  (This file will be used by Tomcat as context description for this web application by renaming and copying it into /conf/Catalina/webapp-10.10.xml)

• Check a WEB-INF/web.xml file of the installed web application, it should contain:
  [code lang="xml"]
  
  ...............
  
  Oracle database
  jdbc/webappdb
  javax.sql.DataSource
  Container
  
  
  [/code]
• Put your JDBC driver (e.g. ojdbc14.jar for Oracle) in $TOMCAT_HOME$/common/lib directory.

RESOURCES:

• DBCP problem “Name jdbc is not bound in this Context”, SOLUTION
• Cannot create JDBC driver of class ” for connect URL ‘null’
• JNDI Datasource HOW-TO
• Commons DBCP – Configuration

I’ve recently faced a problem with overriding static method. I wanted to do something like this:
[code lang="java"]
class A{
protected static void putUsefulInfo(InfoStorage storage){
storage.put(new Info("A"));
storage.put(new Info("B"));
storage.put(new Info("C"));
}
}

class B extends A{
protected static void putUsefulInfo(InfoStorage storage){
A.putUsefulInfo(storage);
storage.put(new Info("D"));
storage.put(new Info("E"));
}

}
[/code]

As a result, I figured out that in ordinary way it is impossible to use polymorphism. An overriden method is just hidden. I’m not going to paraphrase another useful articles, just visit them.

RESOURCES:

• Overriding and Hiding Methods
• Effective object-oriented design
• Overloading, Overriding, Runtime Types and Object Orientation – Overriding Methods

I’m planning to go through Java Certification in the future. Also, one of the my short term goals is to obtain a new job position which would involve Java programming. I haven’t been interviewed since I started working for my current employer. Hence, I must tighten up my knowledge of frequently asked Java essentials and knotty problems.

I’ve made a little investigation using Google and keywords highlighted as post title Java Interview Questions, and here I’m posting a few useful links:

• Interview Questions – Large Number of Java Interview Questions
• SCJP2 Study Notes
• Java Sun Certification official page