In Spoon there are four different kinds of comments:

  • File comments (comment at the beginning of the file, generally licence) CtComment.CommentType.FILE
  • Line comments (from // to end line) CtComment.CommentType.INLINE
  • Block comments (from /* to */) CtComment.CommentType.BLOCK
  • Javadoc comments (from /** to */) CtComment.CommentType.JAVADOC

The comments are represented in Spoon with a CtComment class (javadoc). This class exposes an API to get the content CtComment.getContent(), the type CtComment.getCommentType() and the position CtComment.getPosition() of a comment.

We also try to understand to which element they are attached. We use some simple heuristics that work well in nominal cases but cannot address all specific cases. You can retrieve the comments of each CtElement via the API CtElement.getComments() which returns a List<CtComment>.

The parsing of the comments can be enabled in the Environment via the option Environment.setCommentEnabled(boolean) or the command line argument --enable-comments (or -c).

Javadoc Comments

The Javadoc comments are also available via the API CtElement.getDocComment() but this API returns directly the content of the Javadoc as String.

Comment Attribution

  • Each element can have multiple comments
  • Comments in the same line of a statement are attached to the statement
  • Comments which are alone in one line (or more than one line) are associated to the first element following them
  • Comments cannot be associated to other comments
  • Comments at the end of a block are considered as orphan comments
  • Comments before a class definition are attached to the class

Class comment

// class comment
class A {
  // class comment

Statement comment

// Statement comment
int a; // Statement comment

Orphan comment

try {
} exception (Exception e) {
  // Orphan comment

Multiple line comment

// Statement comment 1
// Statement comment 2 
// Statement comment 3
int a;

Processing Comments

You can process comments like every CtElement.

public class CtCommentProcessor extends AbstractProcessor<CtComment> {
    public boolean isToBeProcessed(CtComment candidate) {
        // only process Javadoc
        if (candidate.getCommentType() == CtComment.CommentType.JAVADOC) {
            return true;
        return false;

    public void process(CtComment ctComment) {
        // process the ctComment

Source Positions

SourcePosition (javadoc) defines the position of the CtElement (javadoc) in the original source file. SourcePosition is extended by three specialized positions:

  • DeclarationSourcePosition (javadoc)
  • BodyHolderSourcePosition (javadoc).

These three specializations are used to define the position of specific CtElement. For example DeclarationSourcePosition is used to define the position of all declarations (variable, type, method, …). This provides an easy access to the position of the modifiers and the name. The BodyHolderSourcePosition is used to declare the position of all elements that have a body.