Solved

Exemples on abstract class and interface

Posted on 1998-03-08
2
321 Views
Last Modified: 2008-03-10
I need some examples to undertand abstract class and interface.
0
Comment
Question by:Zeric
2 Comments
 
LVL 2

Accepted Solution

by:
shogi earned 200 total points
ID: 1233457
You can have 3 way to have an abstract class:
1 - not providing code of one or more method
2 - extends for abstract class and not providing code of one or more method of you extends class.
3 - just writing abstract before the class

About interface:
  Interface it's always abstract, but you don't need to write abstract, the keyword interface includ it.
  In interface you can only have abstract method and static final  constants.  And you need to implements it.

Look examples :
=============================================================
Example on 2 levels of abstract class

/*
     Project: abstract3
*/

import java.lang.*;
import java.io.*;
 
abstract class SuperObjet
{
    abstract public void Categorie();
}

abstract class Mammal extends SuperObjet
{
    public void IndirectCall()
    {
        Food();
    }

    abstract public void Food();
}


class Monkey extends Mammal
{
   public void Food()
   {
      System.out.println("Eat fruits");
   }
   public void Categorie()
   {
      System.out.println("Categorie = Singe");
   }
}

class Tiger extends Mammal
{
   public void Food()
   {
      System.out.println("Eat meats");
   }
   public void Categorie()
   {                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
      System.out.println("Categorie = Tiger");
   }

}

public class abstract3
{
      static public void main(String args[])
      {
//        Vous n'avez pas le droit d'instancier une classe abstraite
//    Mammifere m = new Mammifere();

        Tiger  oTiger  = new Tiger();
        Monkey oMonkey = new Monkey();

        System.out.println("Direct call");
      oTiger.Food();
      oMonkey.Food();

      System.out.println("\nIndirect call to Food (polymorphism)");
      oTiger.IndirectCall();
      oMonkey.IndirectCall();

      System.out.println("\nCategories Methods");
      oTiger.Categorie();
      oMonkey.Categorie();
   }
}

=============================================================
=============================================================
Example on implementing 2 interfaces :

/*
    Projet: interface3
*/

interface TheMother
{
   static final int MotherConst = 100;
   abstract public void MotherMethod();
}

interface First extends TheMother
{
   static final int FirstConst = 200;

   abstract public void FirstMethod();
}

interface Second
{
   static final int SecondConst = 300;
   abstract public void SecondMethod();  
}

class interface3 implements First, Second
{
   public void FirstMethod()
   {
      System.out.println("Calling FirstMethod");
   }

   public void MotherMethod()
   {
      System.out.println("Calling MotherMethod");
   }
   
   public void SecondMethod()
   {
      System.out.println("Calling SecondMethod");
   }

   static public void main(String argv[])
   {
      interface3 interf = new interface3();

      interf.FirstMethod();
      System.out.println("the value of FirstConst is " + FirstConst);
      interf.MotherMethod();
      System.out.println("the value of MotherConst is " + MotherConst);
      interf.SecondMethod();
      System.out.println("the value of SecondConst is " + SecondConst);
   }
}
===============================================================
===============================================================

I hope that it will help you!
0
 

Author Comment

by:Zeric
ID: 1233458
Thanks Shogi
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Where to store the queries for modification of table 4 62
eclipse shortcuts 9 55
tomcat not starting 6 45
pagenation logic how it is working in my code 1 30
After being asked a question last year, I went into one of my moods where I did some research and code just for the fun and learning of it all.  Subsequently, from this journey, I put together this article on "Range Searching Using Visual Basic.NET …
This was posted to the Netbeans forum a Feb, 2010 and I also sent it to Verisign. Who didn't help much in my struggles to get my application signed. ------------------------- Start The idea here is to target your cell phones with the correct…
Viewers will learn about arithmetic and Boolean expressions in Java and the logical operators used to create Boolean expressions. We will cover the symbols used for arithmetic expressions and define each logical operator and how to use them in Boole…
This theoretical tutorial explains exceptions, reasons for exceptions, different categories of exception and exception hierarchy.

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question