$show=/label

Abstraction, Abstract class, methods in Java example

SHARE:

A class which is declared with the abstract keyword is known as an abstract class in Java. It can have abstract and non-abstract methods (method with the body).

Abstract class in Java:

Abstraction defines the ability to make a class as "abstract" declaring with keyword "abstract" which is considered as incomplete.

A class which is declared with the abstract keyword is known as an abstract class in Java. It can have abstract and non-abstract methods (method with the body).

abstract keyword is used to create a abstract class and method. Abstract class in java can't be instantiated. An abstract class is mostly used to provide a base for subclasses to extend and implement the abstract methods and override or use the implemented methods in abstract class


abstract_class


Rules or Conditions of Abstract Class in Java:


1) Once we declare a class "abstract" than object can not created or instantiated for the abstract class. if we try, this will give compile time error.
2) Abstract class can have fields(properties), abstract methods.
3) This can have non-abstract methods.
4) If we declare a method as abstract than no need to provide method body. Whoever is extending this class, they have to provide implementation for the abstract methods.
5) This does not have much importance unless it has sub classes.
6) Abstract methods should be public or protected.

7) Abstraction can be achieved either by declaring class as "abstract" or interfaces.
8) If one method is abstract in any class, that class must declared as "abstract".
9) If sub class does not provide implementation than that sub class must be declared as "abstract".
10) If we do not know the implementation for a method that will be implemented by its sub class, than declare it as abstract.
11) Way to hide implementation.

Example for abstract:

We have mineral water suppliers. We have created a class "WaterCan" declared as abstract and has methods named setDimensions as abstract and manfacPlace.

So whoever is implementing, that class should have implementation for abstract methods.


package com.java.w3schools.core.abstracts;

public abstract class WaterCan {
 public int quantity;
 public abstract void setDimensions(double height, double diameter);
 public String manfacPlace() {
  return "Bangalore";
 }
}


Bisleri brand extends WaterCan.. so need to implement for abstract method. because dimensions can be varied from brand to brand.


class Bisleri extends WaterCan {
 double h;
 double d;
 @Override
 public void setDimensions(double height, double diameter) {
  h = height*1.2;
  d = diameter;
 }
}

Similar to Himalaya brand.


class Himalaya extends WaterCan {
 double h;
 double d;
 @Override
 public void setDimensions(double height, double diameter) {
  h = height * 1.5;
  d = diameter * 0.1;
 }
}

package com.java.w3schools.core.abstracts;
public class BisleriMain {
 public static void main(String[] args) {
  Bisleri bisleri = new Bisleri();
  bisleri.setDimensions(12, 20);
  System.out.println(bisleri.manfacPlace());
 }
}

COMMENTS

BLOGGER: 3
  1. Abstraction in Java
    Real life Example of Abstraction

    Abstraction shows only important things to the user and hides the internal details. Real life example of abstraction is; we know how to ride the bike but we don't know internal function of bike.

    ReplyDelete
Please do not add any spam links in the comments section.

About Us

Author: Venkatesh - I love to learn and share the technical stuff.
Name

accumulo,1,ActiveMQ,2,Adsense,1,API,31,ArrayList,16,Arrays,2,Bean Creation,3,Bean Scopes,1,BiConsumer,1,Blogger Tips,1,Books,1,C Programming,1,Collection,4,Collections,20,Collector,1,Command Line,1,Compile Errors,1,Configurations,7,Constants,1,Control Statements,8,Conversions,5,Core Java,71,Corona India,1,Create,2,CSS,1,Date,2,Date Time API,3,Dictionary,1,Difference,1,Download,1,Eclipse,2,Efficiently,1,Error,1,Errors,1,Exception,1,Exceptions,2,Fast,1,Files,9,Float,1,Font,1,For examples,1,For loop examples,1,For Loop in Java,1,Form,1,Freshers,1,Function,3,Functional Interface,2,Garbage Collector,1,Generics,4,Git,4,Grant,1,Grep,1,HashMap,1,HTML,2,HttpClient,2,Immutable,1,Inner for loops,1,Installation,1,Interview Questions,5,Iterate,2,Jackson API,3,Java,28,Java 10,1,Java 11,5,Java 12,5,Java 13,2,Java 14,2,java 5 For loop,1,Java 8,47,Java 9,1,Java Design Patterns,1,Java Files,1,Java for loop,1,Java Program,2,Java Programs,65,java.lang,5,java.util. function,1,jQuery,1,Kotlin,10,Kotlin Programs,6,Lambda,1,lang,29,Leap Year,1,live updates,1,Math,1,Maven,1,Method References,1,Mockito,1,MongoDB,3,Nested for loop,1,Nested for loop examples,1,New Features,1,Operations,1,Optional,4,Oracle,5,Oracle 18C,1,Partition,1,Patterns,1,Programs,1,Property,1,Python,2,Quarkus,1,Read,1,Real Time,1,Recursion,2,Remove,2,Rest API,1,Schedules,1,Serialization,1,Servlet,1,Softwares,1,Sorting Techniques,8,Spring,2,Spring Boot,23,Spring Email,1,Spring MVC,1,Stream,2,Streams,11,String,48,String Programs,8,String Revese,1,Swing,1,System,1,Tags,1,Threads,7,Tomcat,1,Tomcat 8,1,Troubleshoot,16,Unix,2,Updates,3,util,5,While Loop,1,
ltr
item
JavaProgramTo.com: Abstraction, Abstract class, methods in Java example
Abstraction, Abstract class, methods in Java example
A class which is declared with the abstract keyword is known as an abstract class in Java. It can have abstract and non-abstract methods (method with the body).
https://1.bp.blogspot.com/-NKSApYo17TE/XIoBDJTU0GI/AAAAAAAABIk/oqzbUusT66gy7WW6HNdwLMjMxHt2noF0gCLcBGAs/s640/abstract_class.PNG
https://1.bp.blogspot.com/-NKSApYo17TE/XIoBDJTU0GI/AAAAAAAABIk/oqzbUusT66gy7WW6HNdwLMjMxHt2noF0gCLcBGAs/s72-c/abstract_class.PNG
JavaProgramTo.com
https://www.javaprogramto.com/2015/04/abstraction-abstract-class-methods-in.html
https://www.javaprogramto.com/
https://www.javaprogramto.com/
https://www.javaprogramto.com/2015/04/abstraction-abstract-class-methods-in.html
true
3124782013468838591
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THIS PREMIUM CONTENT IS LOCKED STEP 1: Share to a social network STEP 2: Click the link on your social network Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy Table of Content