How to get correct line number of all methods using javaassist or any other api?

Question

I'm not able to get a correct line of methods. Few are getting properly few are not.

for (CtMethod declaredMethod : declaredMethods) {
        int methodLineNumber = declaredMethod.getMethodInfo().getLineNumber(0);
}

1)What is the mistake?
2)In getLineNumber(int offset) how to calculate offset?

Answer 1

If I understood your question correctly, you are looking on finding out the associated starting line number of all methods in your java code

I would suggest you to use JavaParser (https://javaparser.org/)

Github Link - https://github.com/javaparser/javaparser

It is a java code analysis tool using which I too solved a problem on similar lines

You may need to override the visit method found in VoidVisitorAdapter

private static class MethodStartLine extends VoidVisitorAdapter {
    @Override
    public void visit(MethodDeclaration md, Object arg) {

        System.out.println("METHOD: " + md.getDeclarationAsString() + "STARTS AT" + md.getRange().get().begin.line);

    }
}

You need to set a Compilation Unit and pass it on as below in your driver code

private static void getMethodStartLineNumbers(File src) throws ParseException, IOException {
    CompilationUnit cu = JavaParser.parse(src);
    new MethodStartLine().visit(cu, null);
}

The File src here can be made using the Files.walk() if you need to run it on multiple files

File mySrc = new File(srcRoot, filePath)

where the filePath is the path to file on which you need your java parser to run which can be called with

getMethodStartLineNumbers(File mySrc)

PS: the EBook available on their website gives you great intro to Java Parsers