title: Generic Binary Search Tree Java type argument is not within bounds
body: <p>I did the following binary search tree but it doesn't work... need help</p>
  
  <pre><code>class Tree&lt;ContentType extends Comparable&lt;ContentType&gt;&gt;{
  
  
    Node node;
    public Tree(){
      node = null;
    }
    public Tree(ContentType pContent){
      node = new Node&lt;ContentType&gt;(pContent);
    }
    public Tree(ContentType pContent, Tree pLeftTree, Tree pRightTree){
      node = new Node(pContent);
      node.setLeftTree(pLeftTree);
      node.setRightTree(pRightTree);
    }
    public boolean isEmpty(){
      ...
    }
  
    public void insert(ContentType pContent){
      ...
    } 
  
    public ContentType search(ContentType pContent){
      ...
    }
  
    public void delete(ContentType pContent){
      ...
    }
    public ContentType getContent(){
      ...
    }
  
  
  ...      
  
      private class Node&lt;ContentType&gt;{
          Tree left = null;
          Tree right = null;
          ContentType content = null;
  
  
          public Node(ContentType pContent){
            content=pContent;
            left = new Tree();
            right = new Tree();
  
          }
  
          ... 
  
      }
  
  
  }
  </code></pre>
  
  <p>Now it tells me</p>
  
  <pre><code>type-variable Content-Type#1 is not within bounds of type-variable Content-Type#2.
  </code></pre>
  
  <p>Thanks for all help</p>