clash of types

[t638403]

Hi everyone,

I have a rather basic question here, though I can't figure it out myself.

I want to create a special Node class for use in a search tree. This node I like to call SearchNode which should extend the simpler Node class. The simple Node class looks like this:

public class Node {
   private Node parent;
   private LinkedList<Node> children;
   public void setParent(Node parent) {
      this.parent = parent;
   }
   public void getParent() {
      return this.parent;
   }
   // And some more functions
}

Now I'd like to extend the Node class:

public class SearchNode extends Node {
   private Location loc;
   public SearchNode(Location loc) {
      this.loc = loc;
   }
}

This class has inheritted the functions of Node so in my main loop I want to do the folowing:

SearchNode sn1 = new SearchNode(new Location(10, 12));
SearchNode sn2 = new SearchNode(new Location(45,88));
sn2.setParent(sn1);
SeachNode parent = sn2.getParent();

For obvious reasons it starts complaining that getParent() is going to return a Node, and not a SearchNode (I could cast, but I don't want to). So I want my Node to be more generic. So I figure, let's get into generics :-). So I did something like this:

public class Node<T> {
   T parent;
   public void setParent(T parent) {
      this.parent = parent;
   }
   public T getParent() {
      return this.parent;
   }
}

But as a matter of fact, it keeps complaining. So I figure, I do not have enough knowledge, and I need to ask someone who has :-)

Can anybody help me?

Thanks in advance,
Erik