Java – Ram's Blog

October 3, 2015

My Second Book Published

My second book “Java EE Development with Eclipse – Second Edition” has been published. One of the reasons I did not post much on the blog was this book. I had been working on the book for the past few months and I am very glad that it has been published now.

One of the challenges writing this book was the diverse topics that it covered – Servlets, JSP, JSF, JDO, EJB, JSM, SOAP, REST, Spring, Unit Testing, Debugging and trouble shooting performance and memory issues in Java applications. Separate books could be written, and books have been written, on some of these topics.

This book explains how to develop applications using these technology in Eclipse IDE. The focus is not just on how to use different technologies in JEE, but also on setting up development environment, testing, debugging and deploying applications developed using these technologies.

The book is available on the publisher’s site at bit.ly/1GryrTd.

-Ram Kulkarni

July 22, 2013

Capturing absolute offsets for JavaCC/JJTree tokens

I use JavaCC for generating parsers in Java. And use JJTree to create AST after parsing. JJTree creates nodes of the AST and you can configure JavaCC options to capture tokens in the node – i.e. if you want each node to contain start and end tokens. The default code generated by JavaCC creates Token class with offsets that are relative to the starting offset of the line. It has fields like beginLine, beginColumn, endLine and endColumn. Here the line numbers are absolute line numbers (starting from 1) and column fields contain offsets (again starting from 1) within the corresponding lines.
However many times you want to capture absolute offsets of tokens in the input stream, and not just relative offset in the line. I wish there was a JavaCC option to enable this. But it is not too complex if you want to do it yourself.

To explain how to do this, I will take a grammer file that is generated by the JavaCC wizard of JavaCC Eclipse plugin. This is the default grammer file it generates – Continue reading “Capturing absolute offsets for JavaCC/JJTree tokens”

June 20, 2013

Handling some of the warnings and errors generated by JavaCC

I am currently building a parser using JavaCC. I have used JavaCC in the past, but whenever I use it after a long gap, I have to relearn a few things about it – particularly handling warnings. So I thought this time I would blog about ways to handle some of the frequent warnings that I have seen.

If you are unfamiliar with JavaCC, then it is a parser generator. You create grammer using EBNF (Extended Backus-Naur Form) and feed it to JavaCC. JavaCC then creates Java classes for the parser. I do not want to make this post into JavaCC tutorial. There are some very good tutorials available at JavaCC Documentation page and FAQ. I especially find Lookahead MiniTutorial and Token Manager MiniTutorial very useful. If you use Eclipse IDE, then you would find JavaCC plugin for Eclipse useful – it provides wizard to create JavaCC or JJTree (JJTree creates AST, Abstract Syntax Tree, after parsing the input) files, provides code colorization, outline, code hyper link, syntax checking and compilation. You can also set JavaCC debug options easily using this plugin.

I will use following tokens that are generated by default if you use the wizard provided by JavaCC Eclipse plugin to create a JavaCC grammer file. I have created a .jjt file for examples in this blog.

Continue reading “Handling some of the warnings and errors generated by JavaCC”

July 7, 2012

Using Java Objects in JavaScript in Eclipse SWT Browser Control

I have been developing Eclipse plugins for more than four years now. I have implemented many features in the ColdFusion Builder, which is an Eclipse based IDE. Eclipse SDK provides a SWT Browser control which can be used within Eclipse plugin to display HTML files. Eclipse does not include any browser, but it uses the system browser- on Windows it is Internet Explorer and on Macintosh it is Safari. I have used this control mainly to display static HTML content or open a URL on a remote server, e.g. for executing ColdFusion Builder extensions written in CFML.

Recently I have been doing a lot of mobile application dev elopement, and saw how easy it was to invoke Java objects from JavaScript in Android. I have blogged about this in one of my posts, Creating Android Applications with HTML User Interface. This got me thinking that it would be nice if SWT Browser control would also provide some way to pass Java Objects to JavaScript. Turned out that it is possible.

Continue reading “Using Java Objects in JavaScript in Eclipse SWT Browser Control”