Chapter 13.6, Problem 13.6.6CP

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.

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”.