Java has a generic interface called Comparable. A class that implements the Comparable interface must have a method with this specification:

♦ compareTo
public boolean compareTo(E obj)
Compare this object to another object of the same type.

Returns:
The return value is zero if this object is equal to obj; the return value is negative if this object is smaller than obj; the return value is positive if this object is larger than obj.

Throws: ClassCastException
Indicates that obj is the wrong type of object to be compared with this object.

Write a generic class for a bag of Comparable objects, where the objects are stored in a binary search tree. The tree itself should use the BTNode class from Figure 9.10.

The first line of your new bag class should be: 

public class ComparableTreeBag

> 

This tells the Java compiler that the Comparable- TreeBag is a generic class, but that any instantiation of the generic type parameter E must implement the Comparable interface.

FIGURE 9.10 Specification and Implementation of the Generic Binary Tree Node Class Generic Class BTNode * public class BTNode from the package edu.colorado.nodes A BTNode provides a node for a binary tree with a reference to an E object as the data in each node. Limitations: Beyond Int. MAX_VALUE elements, treeSize is wrong. Specification Constructor for the BTNode public BTNode(E initialData, BTNode initiallLeft, BTNode initialRight) Initialize a node with specified initial data and links to children. Note that a reference to a child may be null, which indicates that there is no child. Parameters: initialData - the initial data of this new node initialleft and initialRight- references to the children of this new node Postcondition: This new node contains the specified data and links to its children. getData-getLeft-getRight public E getData( ) public BTNode getleft( ) public BTNode getRight( ) These are accessor methods to obtain this node's data or a reference to one of the children. Any of these objects may be null. A null reference to a child indicates that the child does not exist. getLeftmostData public E getleftmostData( ) Accessor method to get the data from the leftmost node of the tree below this node. Returns: The data from the deepest node that can be reached from this node following left links. getRightmostData public E getRightmostData( ) Accessor method to get the data from the rightmost node of the tree below this node. Returns: The data from the deepest node that can be reached from this node following right links.