Classes : It is like skeleton from which we make our objects
Objects : They are real-world examples.
Instance : The object which is currently in memory .
Inheritance :
Using one class methods and varibales in other classes.
In java , you cannot have two classes inhertied into one unlike C++. Only one class be inherited. But multi-level inheritance is supported .
Ex :
Class A
Class B
Class C inherits Class A and Class B This is not supported in Java. Multiple Inheritance
but
Class B inheirts Class A
Class C inherits Class B this is supported.
Syntax in java
Class A {}
Class B extends Class A{} Simple :)
Polymorphism : Changing of existing methods to suite new object requirement.
In Java we use
Method Overloading : Number and types of arguments will change
Method Overriding :
Abstraction : This is what common across some objects/class. Like car, ship , bus , they all transport people.
So we can define new class having the common characteristic and reuse(inherit) it .
Encapsulation : This is main reason of defining class. To have variables and thier methods bind together of a class. The process of binding variables and methods to an abstract class.
Information hiding : Simply means which variables/methods you want to expose.
Use of Public and private
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Class Modifiers :
For Access : Public > can be accessed from any classes.
Private >
Protected
default
For App method :
Final
Abstract
static
Member Variable
Acess : private, public,protected,default
App : final , static
Member Method : Will focus only on those which are defined for Varibales
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