Abstraction in Java - Hiding Implementation Details

Abstraction

Data abstraction is the process of hiding certain details and showing only essential information to the user.

Abstract class: can have abstract and non-abstract methods. Abstract method: can only be used in an abstract class, and it does not have a body. The body is provided by the subclass.

abstract class Animal {
  public abstract void animalSound();
  public void sleep() {
    System.out.println("Zzz");
  }
}
class Pig extends Animal {
  public void animalSound() {
    System.out.println("The pig says: wee wee");
  }
}