Tree Implementations - Data Structures and Abstractions with Java - page 602

/** Copies the subtree rooted at this node.
@return the root of a copy of the subtree rooted at this node */
public BinaryNodeInterface<T> copy();
} // end BinaryNodeInterface

These nodes have more responsibilities than the nodes in a linked chain. Soon you will see
how the last three methods in this interface simplify the implementation of the binary tree. But first
we will implement this interface as the class BinaryNode .

An Implementation of BinaryNode
24.3

Since we want to hide the node from clients of the binary tree, we place BinaryNode within
TreePackage , along with BinaryNodeInterface , and omit its access modifier. We present a portion
of the implementation of BinaryNode in Listing 24-1.

LISTING 24-2

The class BinaryNode

package TreePackage;
class BinaryNode<T> implements BinaryNodeInterface<T>
{

private T data;
private BinaryNode<T> left;
private BinaryNode<T> right;

public BinaryNode()
{

this ( null ); // call next constructor
} // end default constructor

public BinaryNode(T dataPortion)
{

this (dataPortion, null , null ); // call next constructor
} // end constructor

public BinaryNode(T dataPortion, BinaryNode<T> leftChild,
BinaryNode<T> rightChild)

{

data = dataPortion;
left = leftChild;
right = rightChild;
} // end constructor

public T getData()
{

return data;
} // end getData