Illustrate inheritance and composition?, JAVA Programming

The 'is a' relationship is used with inheritance and 'has a' relationship is used with composition. Both composition and inheritance allow you to perform sub-objects inside your new class. Two of the main techniques for code reuse are object composition and class inheritance.

378_Untitled.png

 

Inheritance is single-directional. For example man is a human. But human is not a man. Inheritance needs extends key word. Composition: is used when Man has an eye. It is incorrect to say man is an eye. Composition simply defines using instance variables that refer to other objects. The class man will have an instance variable, which refers to an eye object.

 

 Which one to favor, inheritance or composition? The guide is that inheritance could be only used when subclass 'is a' superclass.

1. Don't use inheritance just to get programming code reuse. If there is no 'is a' relationship then require composition for code reuse. Overuse of implementation inheritance will divide all the subclasses, if the superclass is changed.

 

2. Do not add inheritance just to get polymorphism. If there is no 'is a' relationship and all you need is polymorphism then use interface inheritance with composition, which provides you code reuse.

 

Posted Date: 7/25/2012 12:49:02 AM | Location : United States







Related Discussions:- Illustrate inheritance and composition?, Assignment Help, Ask Question on Illustrate inheritance and composition?, Get Answer, Expert's Help, Illustrate inheritance and composition? Discussions

Write discussion on Illustrate inheritance and composition?
Your posts are moderated
Related Questions
two different object may have chance to have same behavier but property must be different why?

What is difference between Design and System Architecture? System architecture is the conceptual design which defines the structure and/or behavior of a system. Whereas designs

Question 1 Describe any five buzz words in Java Question 2 Describe exception classes and also explain common exceptions in java Question 3  Describe primitive and

Problem description: A travelling salesman wants to make a tour of the cities and returns back to the starting point. What is the minimum length tour? Formal Definiti

String is immutable in java : you can't change a string object but can replace it by creating a new object instance. Creating a new instance is rather expensive.   //Non ef

What does the keyword " synchronize " mean in java. What are the usage and disadvantages of synchronization?

Android App Development Project Description: I am seeking a developer who can start an app from scratch and get it delivered to me as soon as possible. It is a minute android

I am having an combox box and values are retrieved from the database having inputs and labels i want to created the dynamic form accroding to user input on combox box values


Problem statement Part 1 Write an aspect that counts different kinds of method calls in a Java program. Your aspect should meet the following requirements:  The aspect should ma