JAVA-OOPS: ABSTRACTION

This post covers the topic Abstraction

 ABSTRACTION:

• Hiding the implementation part is called abstraction
• It has 2 types,
1. Partial abstraction (abstract class)
2. Full abstraction (interface)

1. Partial Abstraction (Abstract class):

• It will support abstract method and non-abstract method.
• We can’t create object for abstract class because in the method signature we didn't mention any business logic.
• In abstract method, we only mention abstract signature, won't create business logic
• It have 2 class, abstract class (sub class) and super class. we create object and business logic only in super class, won't create in abstract class

Example Program:

abstract class

public abstract class Bank {
    abstract void saving();        //method signature
    abstract void current();
    abstract void salary();
    abstract void joint();
    public void branchDetails(){
    System.out.println("chennai");
    }
}

super class

public class AxisBank extends Bank {
    public void saving() {         // method signature
        System.out.println("saving regular");         // business logic
    }
    public void current() {
        System.out.println("current");
    }
    public void salary() {
        System.out.println("salary");
    }
    public void joint() {
        System.out.println("joint");
    }
public static void main(String[] args) {
    AxisBank info = new AxisBank();

    info.branchDetails();

    info.salary();

    info.saving();

    }

}

Output:

chennai

salary

saving

2. INTERFACE / FULL ABSTRACTION;

• It will support only abstract method, won't support non abstract method
• In interface "public abstract" is default. we no need to mention
• It is using implements keywords

Example Program:1

interface

public interface Bank {

    abstract void saving();

    abstract void current();

    abstract void salary();

    abstract void joint();

    public void branchDetails();

}

super class

public class AxisBank implements Bank {

    public void saving() {

        System.out.println("saving regular");

    }

    public void current() {

        System.out.println("current");

    }

    public void salary() {

    System.out.println("salary");

    }

    public void joint() {

    System.out.println("joint");

    }

    public void branchDetails() {

    System.out.println("chennai");

    }

public static void main(String[] args) {

    AxisBank info = new AxisBank();

    info.branchDetails();

    info.salary();

    info.saving();

    }

}

Output:

chennai

salary

saving regular

• multiple inheritance its won’t support in java but using interface its support
• here we have to create 2 interface(super class) and one sub class(normal). In the sub class we implement both interface

Example Program:2

interface

public interface ABank {

    public void test();

    }

    public interface HBank {

    public void test();

    }

sub class (normal class)

public class Bank implements ABank, HBank{

@Override

    public void test() {

    }

}

Abstract class	Interface
Partial abstraction	Full abstraction
It support both abstract method and non-abstract method	It support only abstract method
It’s using "extends" keyword	It’s using "implement" keyword
Here "public abstract" have to mention	"public Abstract" is default. no need to mention
We can use whatever access specifier we want	Here we use only public (access specifier)