Can't delete an object from a set

Question

I need to delete a comment from a Set<Commentaries>. And it worked! But I try with the code below, it doesn't work. After I ordered my Set by using a TreeSet with MyComparator

@RequestMapping("/user/editPage/{idContractor}")
public String goToEditPage(@PathVariable("idContractor") Integer idContractor, Model model) {

.....

Set<Commentaries> comSet = contractorsWithId.getCommentarieses();
TreeSet<Commentaries> treeComment = new TreeSet<Commentaries>(new MyComparator());
treeComment.addAll(comSet);
contractorsWithId.setCommentarieses(treeComment);

return "user/editPage";
}

//Below my method for delete

public void removeCommentaries(Commentaries commentToDelete, Contractors contractorWithID) {
    contractorWithID.getCommentarieses().remove(commentToDelete);
    contractorsService.update(contractorWithID);
}

Help me please! I'm new to stackoverflow and if something you don't understand I can edit my question!

Answer 1

• while working with TreeSet make sure your Comparator gives a correct result.
• In your case MyComparator comparing on which field is important.
• If Comparator return 0 means two comments are same which will not be added to treeset while doing treeComment.addAll(comSet);
• If comment not gets added to treeset which mean you can't remove it.
• though all collections gives you return flag on remove check that. If it is false means that comment was not present in treeset.

The problem with specific code will help.

Answer 2

I have creates simple example, but it works. Please, correct me:

public class Main
{
   static Contractors con = new Contractors();

   static Commentaries com = new Commentaries("TROL");

   static
   {
      con.getCommentarieses().add(new Commentaries("1A"));
      con.getCommentarieses().add(new Commentaries("2B"));
      con.getCommentarieses().add(com);
      con.getCommentarieses().add(new Commentaries("3C"));
   }

   public static void main(String[] args)
   {
      Set<Commentaries> comSet = con.getCommentarieses();
      TreeSet<Commentaries> treeComment = new TreeSet<>((a1, a2) -> {return a1.name.compareTo(a2.name);});
      treeComment.addAll(comSet);
      con.setCommentarieses(treeComment);

      removeCommentaries(com, con);

      System.out.println(con);
   }

   public static void removeCommentaries(Commentaries commentToDelete, Contractors contractorWithID) 
   {
      contractorWithID.getCommentarieses().remove(commentToDelete);
   }
}

Object is removed like expected