Java nested classes

Question

I need to implement a red-black search tree in java. I thought about creating two class: RBTree and RBNode, where RBNode is nested inside RBTree (this is the demand of the exercise).

RBNode should have the following fields:

key, value, color - no problem with that.

parent, leftChild, rightChild - which are also RBNode type. This I cannot seem to implement, because in order to create an instance of an RBNode, I need an instance of RBTree.

This is my code:

public class RBTree {


public RBNode createNode() {
    return this.new RBNode();
}



    class RBNode{

      private int key;
      private RBTree.RBNode rightChild = new RBTree.RBNode(); \//the problem is here

      public RBNode() {


        this.rightChild=null;
        this.key=-1;



      }  

}

    public static void main(String[] args) {

        RBTree t = new RBTree();
        RBNode rb = t.createNode();
        System.out.println(rb.key);
        System.out.println(rb.rightChild.key);
    }


}

I would appreciate any ideas how to solve this.

Thanks.

Rahul · Accepted Answer · 2012-12-08 08:59:42Z

2

there is no point in making RBNode as a nested class. Make RBNode a separate class and store a reference to RBNode in RBTree. It should solve your problem.

In case, you want to make a nested class, make it static class so that you dont have to instantiate the parent class to instantiate RBNode.

new RBTree.RBNode();

should work if change class declaration of RBNode to

static class RBNode{}

answered Dec 8, 2012 at 8:59

Rahul

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Comments

Joop Eggen · Accepted Answer · 2012-12-08 08:59:36Z

0

You need only use RBNode, not RBTree.RBNode. Furthermore do you really need a parent? RBNode can be private static.

answered Dec 8, 2012 at 8:59

Joop Eggen

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