JavaParser doesn't update source file

Question

I'm using JavaParser and following its Wiki. Problem is even though I change the method's name and add a parameter to it, the file doesn't update. In other words, changes are not saved. When I System.out.println the changed CompilationUnit, it prints it with changes, but those changes don't affect the source file at all.

Is there anything like CompilationUnit.update() or am I missing something ?

The example I've used from the Wiki:

    files_list = FilePicker.chooseAndGetJavaFiles();

    if (files_list == null || files_list.isEmpty()) {
        Errors.showError(Errors.COMMENT_GENERATOR_FILELIST_NULL_OR_EMPTY);
    } else {

        CompilationUnit cu = null;
        FileInputStream in = new FileInputStream(files_list.get(0));
        try {
            cu = JavaParser.parse(in);
        } catch (ParseException ex) {
            Logger.getLogger(CommentGenerator.class.getName()).log(Level.SEVERE, null, ex);
        } finally{
            in.close();
        }
        new MethodChangerVisitor().visit(cu,null);

        System.out.println(cu.toString());
    }
}

private static class MethodChangerVisitor extends VoidVisitorAdapter{

    @Override
    public void visit(MethodDeclaration n, Object arg) {
       // change the name of the method to upper case
        n.setName(n.getName().toUpperCase());

        // create the new parameter
        Parameter newArg = ASTHelper.createParameter(ASTHelper.INT_TYPE, "value");

        // add the parameter to the method
        ASTHelper.addParameter(n, newArg);

    }


}

EDIT: Here is the solution; Add Below Line;

Files.write(new File("Modified.java").toPath(), cu.toString(), StandardCharsets.UTF_8);

---

Change Below Line to use Special Characters as well(e.g "ş,ö,ü ...)

cu = JavaParser.parse(files_list.get(0));

To

cu = JavaParser.parse(files_list.get(0),"UTF-8");

Answer 1

Since you already have the string representation, what about this:

Files.write(new File("Modified.java").toPath(), cu.toString(), StandardCharsets.UTF_8);