How to generate AST from Java source-code?

As far as I know, the only way to parse Java source-code into an AST (Abstract Syntax Tree) is to use the Java Compiler Tree API: com.sun.source.tree

I have two questions:

1. What JDKs support com.sun.source.tree?
2. Is there a portable replacement that works for all JDKs?

Regarding your second question, there are dozens of Java parsers available in addition to Sun's. Here is a small sample:

• Eclipse's org.eclipse.jdt.core.dom package.
• Spoon outputs a very nice annotated parse tree with type information and variable binding (and uses Eclipse's parser internally)
• ANTLR is a parser-generator, but there are grammars for Java available
• javaparser (which I have not used)

My best advice is to try each of them to see which works best for your needs.

You can possibly take the tools.jar and use it. javac is open source so you can just grab that code (assuming you can deal with the license). Antlr has grammars for Java as well.