Handling currency calculations in Java business application

Recently I saw a weird floating issue in Java application which made our currency calculation wrong. Can you guess what would be the output of the below code?

System.out.println(38.0 - 26.6);

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Java – Thread’s stack trace dump

Recently I was dealing with a deadlock issue. Usually I use eclipse break points to create deadlock situation at the same time find the line/code which causes the deadlock. But this one is bit complex scenario where it is not easy to have break points move line by line to reproduce the deadlock. Read more of this post

A JSP code to debug class loader issues

Class Loader is one of the complex concept/design to understand in Java programming. On the initial days working with Tomcat and Desktop application there is not much class loading issues. From EJB days class loading became complex by specification and implementation. Seems JavaEE 5 tries to simplify the class loading specification but I don’t know much about that. Read more of this post

Is UML dead? & What is the future of UML?

Once upon a time UML is a hot buzz word in software development industry. If you know what is aggregation, abbreviation, etc. you will get job easily as an architect. Tools like Rational Rose are costly only a few company had that tools. Read more of this post

Is design pattern teaches how to design an application?

Many of them think that if a person knows design pattern (the theory), he/she can design an application; due to this misunderstanding many stupid questions been asked in interviews about design pattern in a meaningless way. Read more of this post

JEXL – A simple expression evaluation engine

When I was developing a framework looking for a solution very similar to eval() function in JavaScript. Initially I thought of Velocity but somehow I wasn’t convinced with that approach. (Struts2 uses Velocity to externalize the HTML generation to make it customizable). Later I wrote my own parser to evaluate an expression that returns a Boolean value. Recently I found an open source which exactly meets my requirement. I don’t have to talk much about this open source you can find lot more information in their website. I thought it might be useful to others as well.
Reference: http://commons.apache.org/jexl/

JDBC performance tuning with optimal fetch size

Tuning performance using fetch size is an old technique some of you might already be using this configuration; some may know about it but may not have implemented. Recently I have implemented in my current project, would like to share my experience. In a typical production environment database and application will be running on different physical server. Even if you have high-end server class machine the network traffic between application and database server is one of the key factor of your application performance. Read more of this post