Parsing Java Source Code

Question

I am asked to develop a software which should be able to create Flow chart/ Control Flow of the input Java source code. So I started researching on it and arrived at followi

Answer 1

Our DMS Software Reengineering Toolkit is general purpose program analysis and transformation machinery, with built in capability for parsing, building ASTs, constructing symbol tables, extracting control and data flow, transforming the ASTs, prettyprinting ASTs back to text, etc.

DMS is parameterized by an explicit language definition, and has a large set of preexisting definitions.

DMS's Java Front End already computes control and data flow graphs, so your problem would be reduced to exporting them.

EDIT 7/19/2014: Now handles Java 8.

Answer 2

The way I would do it is to analyse compiled code. This would allow you to read jars without source and avoid parsing the code yourself. I would use Objectwebs ASM to read the class files.

Answer 3

I'd go with Antlr and use an existing Java grammar: https://github.com/antlr/grammars-v4

Answer 4

All tools handling Java code usually decide first whether they want to process the language Java or Java byte code files. That is a strategic decision and depends on your use case. I could image both for flow chart generation. When you have decided that question. There are already several frameworks or libraries, which could help you on that. For byte code engineering there are: ASM, JavaAssist, Soot, and BCEL, which seems to be dead. For Java language parsing and analyzing, there are: Polyglot, the eclipse compiler, and javac. All of these include a complete compiler frontend for Java and are open source.

I would try to avoid writing my own parser for Java. I did that once. Java has a rather complex grammar, but which can be found elsewhere. The real work begins with name and type resolution. And you would need both, if you want to generate graphs which cover more than one method body.

Answer 5

Smarter solution is to use Eclipse's java parser. Read more here: http://www.ibm.com/developerworks/opensource/library/os-ast/

Answer 6

Now I have two ways of recognizing:

You have many more ways than that. JavaCC ships with a Java 1.5 grammar already built. I'm sure other parser generators ditto. There is no reason for you to either have to write your own grammar or construct your own parser.

And specifically 'read[ing] input source code files as text and search for the specific patterns' isn't a viable choice at all, as it isn't parsing, and therefore cannot possibly recognize Java programs correctly.