What is Abstract methods?

**ScarFace 01** · 09-02-2010

Hi friends,

I am new to the programming. Currently I am learning Java programming. But I am getting troubled while understanding the concept of 'Abstract methods'. I want to be aware about the use of 'Abstract methods' in java programming. I wonder if you are able to help me know about the 'Abstract methods'. I would greatly appreciate you any help over 'Abstract methods'.

**opaper** · 09-02-2010

In Pascal keywords abstract or virtual are used in the class type declaration at the end of the line to specify what will be virtual or abstract methods. An interface is a Java class which comprises only abstract methods and doesn't implement any field there is to say methods without declaration. It serves as a formalism for classes that implement it. The abstract methods of the interface are accessible only from classes that implement the interface and these classes must be redefined by implementing.

**MindSpace** · 09-02-2010

Hi friend, Please refer following example of 'Abstract methods':

Code:

public abstract class Shape1
{
    
 //...Class implementation

    public abstract void Draw1(int xm, int ym) //...Abstract method declaration

    {
        
    } 
}


public abstract class Shape2D1 : Shape1

{ //Class implementation

    
}

public class Cricle1 : Shape2D1
{
    
    public override void Draw(int xm, int ym)
    {
        
    }

}

**Modifier** · 09-02-2010

A class abstract describes the behavior Common and full a set objects, even if some of these behaviors can be located at this level must still declare them (abstract). Do not declare abstract methods that would not make sense for all subclasses. Java will not create an instance of abstract method, it is logical if we could do then we would get an object not fully implanted. A class may, of course, be declared abstract same if it contains no methods abstract.

**Praetor** · 09-02-2010

Hi,

Below given example depict you the use of abstract methods:

Code:

abstract class Abter1
{
    abstract void Abter1();
    public long repeat(int c){
        long start = System.currentTimeMillis();
        for (int i=0; i<c; i++) benchmark();
        return(System.currentTimeMillis()-start);
    }
}
class MDAbter1 extends Abter1
{
    void Abter1(){};
    public static void main(String[] args)
{
        int d=Integer.parseInt(args[0]);
        long time = new MethodBenchmark().repeat(c);
        System.out.println(c+" methodes en "+time+" millisecondes");
    }
}

**Katty** · 09-02-2010

Implement all the abstract methods is always inherited which is referred as concrete class. Abstract class must not be instantiated. This type of class naturally extend to use it. A subclass of this class is abstract only if it still does not define all abstract methods it inherits. The methods that states without giving them an implementation must be declared abstract with keyword abstract. Abstract class which adds a service to its abstract methods.