Chapter 13.6, Problem 13.6.2CP

Program Plan Intro

Interface:

Interface is a reference type in Java, which contains a collection of abstract methods.

An interface needs to the follow certain conditions such as:

• One cannot instantiate an interface.
• Interfaces do not contain any constructors.
• All methods present in the interface are abstracts.
• An interface does not contain any instance field.
• An interface cannot be extended by a class.

Comparable Interface:

A comparable interface is a generic interface that defines the compareTo() method that is used for comparing objects.

Using comparable interface, one can choose the properties of the objects, rather than the reference location of the objects.

Example:

//java langauage package for comaprable interface

package  java.lang

//comparable interface definition

public interface Comparable <E>

{

     //use of compareTo to compare objects

public integer compareTo(E o);

}

The compareTo() method determines the order of this object with the specified object “o” and returns a negative integer, zero or positive integer, if this object is less than, equal to or greater than object “o”.