Friday, June 19, 2009

Weekly Source Code: LINQ for Java

Its been a long couple of weeks due to my current work load, working average 12 hours+ per day isn't fun. So I finally got some free time over a lunch break to continue with my weekly source code.

At work Java is our main programming language but its not so advance like C# (not to start a language war here!) one of them are LINQ but LINQ is also available in Java!

What Is LINQ?

Language Integrated Query (LINQ) was added to C# 3.0 / VB.Net 9.0 in MS Visual Studio.Net 2008. Its a query language part of the underline language for easy query of information like a database, online resources like a webservice or in our case collections (list, arrays, hashmaps etc). Different LINQ providers existing for collections, databases, Amazon, Facebook, Twitter, LDAP etc. Visit Wikipedia for more about LINQ.

Let's Meet: JoSQL

JoSQL is LINQ for Java that allow you to easily query collections (lists, arrays etc) using a SQL line syntax.



  • No compile time checking since the LINQ code will only be evaluated when query.parse() method get called at run-time.
  • You need to indicate the full package + class name in your query
  • If you wish to use "NOT IN" or "IN" in the WHERE clause then you need to override the toString() method of the class since it needs to know which field to use to do the comparison with.

I will write more JoSQL samples in the next weekly source code. Also my solution to the toString() problem.

1 comment:

Timo Westkämper said...

For a typesafe approach to LINQ for Java, consider Querydsl

Querydsl supports JPA/Hibernate, JDO, SQL and Collections as backend and has a fully typesafe syntax like LINQ.