OOPS concepts in Java
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Java basics concepts
Java Objects and Classes
What is Inheritance in Java?
What is Abstraction in Java?
What is Interface in Java?
What is Abstract Class in Java?
What is Polymorphism in Java?
What is Encapsulation in Java?
Java programming example
How Java Program Work?
Hello World in Java
Java basics for beginners
Abstract class:
Abstract class
defines a class that contains the abstraction without providing a complete
implementation of method. The abstract keyword is used for abstract class and
abstract method.
Abstract classes are used if you want to create a super class
that only defines the variables and methods and sub class will be accessed the
variables and methods for implementation.
Abstract class
defines a class that contains the abstraction without providing a complete
implementation of method. The abstract keyword is used for abstract class and
abstract method.
Abstract classes are used if you want to create a super class
that only defines the variables and methods and sub class will be accessed the
variables and methods for implementation.
Rule of Abstract class.
1. Abstract classes may or may not contain abstract methods.
2. Must be
declared abstract keyword if a class has at least one abstract method.
3. The class
cannot be instantiated if abstract is declared.
4. Must be
provided implementations of all the abstract methods, If you inherit
an abstract class.
Example:
abstract class Figure {
double dim1;
double dim2;
Figure(double d1,double d2){
dim1
= d1;
dim2
= d2;
}
abstract void area();
}
class Rectangle extends Figure{
Rectangle(double d1,douple d2){
super(d1,d2);
}
//Override area of rectangle
void area(){
System.out.println("area
of rectangle is"+ dim1*dim2);
}
}
class Demo{
public static void main(String
args[]){
Figure
f = new Rectangle(4,7);
f.area();
}
Output:
area
of rectangle is 28
1. Abstract classes may or may not contain abstract methods.
2. Must be
declared abstract keyword if a class has at least one abstract method.
3. The class
cannot be instantiated if abstract is declared.
4. Must be
provided implementations of all the abstract methods, If you inherit
an abstract class.
Example:
abstract class Figure {
double dim1;
double dim2;
Figure(double d1,double d2){
dim1
= d1;
dim2
= d2;
}
abstract void area();
}
class Rectangle extends Figure{
Rectangle(double d1,douple d2){
super(d1,d2);
}
//Override area of rectangle
void area(){
System.out.println("area
of rectangle is"+ dim1*dim2);
}
}
class Demo{
public static void main(String
args[]){
Figure
f = new Rectangle(4,7);
f.area();
}
Output:
area
of rectangle is 28
