Abstract class and Methods

Java Abstract class

• An abstract class is a class that cannot be instantiated
• Which means we cannot create objects for an abstract class
• We use keyword abstract to create an Abstract class
• If we try to create object for an Abstract class we will get an error
• To access methods of an Abstract class we need to create a subclass
• An abstract class can have both abstract and non-abstract methods

Syntax

abstract class Example {
	//methods
}

If we try to create object as we do for a normal class, the output will be an error as below

Example is abstract; cannot be instantiated

Java Abstract Method

• An abstract method is created without the definition
• Abstract methods can only be created inside an Abstract class
• If we create an Abstract method inside a non-abstract class it will throw a error

Example

abstract class Example {
	abstract void read ();
	public void show () {
		System.out.println('Hey');
	}
}

Inheriting an Abstract class

To access the attributes and methods of an abstract class we need to inherit to a class.

abstract class A {
   abstract void show();
}

class B extends A {
   public void show() {
      System.out.println("function called");
   }
}
class Main {
   public static void main(String[] args) {
      B d1 = new B();
      d1.show();
   }
}

check output here