Checking Java code fragments using eclipse AST

Question

I'm trying to check for syntactical and logical correctness some Java code fragments using the eclipse abstract syntax tree.

I did some research on how this could be done, I read the documentation, but I haven't found a clear example.

So, I want to check for correctness a set of statements, something like:

System.out.println("I'm doing something");
callAMethod(7);
 System.out.println("I'm done");**sdsds**

Something like that. You got the point. Here, sdsds should be signaled as erroneous.

My question is how can I detect if the Java text is incorrect syntactically or lexically? And how can I get the messages describing the errors?

My code for that is:

ASTParser parser = ASTParser.newParser(AST.JLS3);
parser.setKind(ASTParser.K_STATEMENTS);
parser.setSource(textToParse.toCharArray());
parser.setResolveBindings(false); 
ASTNode node = (ASTNode) parser.createAST(null); 
 // If MALFORMED bit is 1, then we have an error. The position of MALFORMED 
 being 1, then this should detect the error. **But it doesn't. What's the problem?**
    if (node.getFlags() % 2 == 1) { 
    // error detected
}

if (node instanceof CompilationUnit) {
    // there are severe parsing errors (unrecognized characters for example)
    if (((CompilationUnit) node).getProblems().length != 0) {
        // error detected
    }
}

Hope somebody can help me. Thanks a lot!

Answer 1

If you change the parser kind to K_COMPILATION_UNIT and invoke the parser then you can ask the returned compilation unit for problems.

    parser.setKind(ASTParser.K_COMPILATION_UNIT);
    final CompilationUnit cu = (CompilationUnit) parser.createAST(null);
    IProblem[] problems = cu.getProblems();
    for(IProblem problem : problems) {
        System.out.println("problem: " + problem.getMessage() + problem.getSourceStart());
    }