Learn ABSTRACTION in 9 minutes! 🌫️

#java #javatutorial #javacourse

public class Main {
public static void main(String[] args) {

// abstract = Used to define abstract classes and methods.
// Abstraction is the process of hiding implementation details
// and showing only the essential features.
// Abstract classes CAN'T be instantiated directly.
// Can contain 'abstract' methods (which must be implemented)
// Can contain 'concrete' methods (which are inherited)

Circle circle = new Circle(3);
Triangle triangle = new Triangle(4, 5);
Rectangle rectangle = new Rectangle(6, 7);

circle.display();
triangle.display();
rectangle.display();

System.out.println(circle.area());
System.out.println(triangle.area());
System.out.println(rectangle.area());
}
}
public abstract class Shape {

abstract double area(); // ABSTRACT

void display(){ // CONCRETE
System.out.println("This is a shape");
}
}

public class Circle extends Shape{

double radius;

Circle(double radius){
this.radius = radius;
}

@Override
double area(){
return Math.PI * radius * radius;
}
}

public class Triangle extends Shape{

double base;
double height;

Triangle(double base, double height){
this.base = base;
this.height = height;
}

@Override
double area(){
return 0.5 * base * height;
}
}

public class Rectangle extends Shape{

double length;
double width;

Rectangle(double length, double width){
this.length = length;
this.width = width;
}

@Override
double area(){
return length * width;
}
}