Answers for "abstraction in java"

abstraction java

bstraction: Hiding the implementation details, 
concentrating on essentials things, 
without worrying about the details 
■ In java, abstraction is achieved via abstract class or interface 
■ Abstraction cannot exist without inheritance 

3.1. Abstract class a class that's meant to be inherited 
(cannot be private or final)
■ To create an abstract class: add keyword abstract 
before the class declaration 
■ A class that we cannot create object 
when abstract class extended by regular class: 
we MUST override all the abstract methods of super class
when abstract class extended by abstract class: 
no need to override any abstract methods

abstract class vs non-abstract class:
NON-ABSTRACT CLASS:
cannot have: abstract methods
can have: constructor, instance method, static method, 
instance block, static block, instance variable, static variable
ABSTRACT CLASS:
can have: constructor, instance method, static method, instance block,
static block, instance variable, static variable...
ABSTRACT METHOD: method without implementation, meant to be override 
(cannot create object, cannot be final,static,private)

FRAMEWORK EXAMPLE:
In my framework I have achieved abstraction by using collections 
or Map, because it’s all interface. Most of the cases I come 
across using List. If we want to access elements frequently 
by using index, List is a way to go. ArrayList provides 
faster access if we know index. If we want to store elements and 
want them to maintain an order, List is a better choice. 
i) List webs = driver.getWindowHandles();    
=>create a list first to store web URLs in list
ii)To handle dynamic elements store it in the list and identify by index
List all = driver.findElements(By.tagname(“”));
In my framework I follow POM and had situations where some pages 
shared similar actions that were similar but worked slightly 
different, so I was able to use abstraction to define those 
actions and implement them in each page according to what was needed 
for that webpage

what is abstraction in java

Sometimes we may come across a situation
where we cannot provide implementation to
all the methods in a class. We want to leave the 
implementation to a class that extends it.
  In that case we declare a class
as abstract by using abstract keyword on method
signature.In my framework I have created my
PageBase class as super
class of the all page classes. 
I have collected all common elements
and functions into PageBase class and
all other page classes extent PageBase class.
By doing so, I don't have to locate very
common WebElements and it provides
reusability in my framework.
Also
1)Abstract classes cannot be instantiated
2)An abstarct classes contains abstract method,
concrete methods or both.
3)Any class which extends abstarct class must
  override all methods of abstract class
4)An abstarct class can contain either
  0 or more abstract method.

Abstraction in java

// example on abstract class in java
import java.util.*;
// abstract class
abstract class Shape
{
   // abstract method
   abstract void sides();
}
class Triangle extends Shape
{
   void sides()
   {
      System.out.println("Triangle shape has three sides.");
   }
}
class Pentagon extends Shape
{
   void sides()
   {
      System.out.println("Pentagon shape has five sides.");
   }
   public static void main(String[] args)
   {
      Triangle obj1 = new Triangle();
      obj1.sides();
      Pentagon obj2 = new Pentagon();
      obj2.sides();
   }
}