Overriding compareTo on self-referencing object (parent/child relationship)

Question

I'm trying to implement compareTo on a domain class in grails so I can return a SortedSet. I want my sorted set to be ordered by parent name, then by "child" name. For example (P=parent, C=child):

• P-1
  • C-1
  • C-2
• P-2
  • C-3
  • C-4

My class looks something like this:

class Issue implements Comparable {
 String name
 Issue parent

@Override
public int compareTo(obj){
  if(obj.parent!=null && this.parent!=null){
   parent.name.compareTo(obj.parent.name)
  }else{
      //What do I compare to sort the children relative to their parents?
  }
}

Answer 1

If all you're looking for is sorted sets, would just implementing Comparable on Issue and using sort orders on the mappings suffice?

class Issue implements Comparable {
 String name
 Issue parent
 SortedSet children

 static hasMany = [children : Issue]
 static belongsTo = [parent : Issue]
 static mapping = {
    sort 'name'
    children sort:'name'
 }    

@Override
public int compareTo(obj){
  if(obj){
    this.name?.compareTo(obj.name)
  }
}