content: public class Pillers {
      public static void main(String args[]) {
          // Pillers
          // (i) Encapsulation (ii) Inheritance (iii) Polymorphism (iv) Abstraction
  
          Fish shark = new Fish(); // Inheritance - Single level
          shark.eat(); // Animal's functiion this mean here happening Inheritance
          shark.swim(); // Fish's function
  
          Dog doggy = new Dog(); // Inheritance - Multi level
          doggy.eat(); // Animal1's function
          doggy.legs = 4; // Mammal's property
          System.out.println(doggy.legs);
  
          Fish1 tuna = new Fish1(); // Inheritance - Hierarchial
          tuna.breath();
          tuna.swim();
          Bird parrot = new Bird();
          parrot.eat();
          parrot.fly();
  
          Mammals m = new Mammals(); // Inheritance - Hybrid
          m.breath();
          Human h = new Human();
          h.mammalEats();
          h.humanLegs();
          Lion l = new Lion();
          l.mammalSleep();
          l.lionRoars();
          Birds b = new Birds();
          b.eat();
          Peacock p = new Peacock();
          p.birdFly();
          p.peacockDance();
          Parrot tota = new Parrot();
          tota.birdFly();
          tota.parrotColor();
          Fishes f = new Fishes();
          f.breath();
          f.eat();
          Shark s = new Shark();
          s.fishSwims();
          s.sharkFish();
          Rohu r = new Rohu();
          r.fishSwims();
          r.rohuFish();
      }
  }
  // (I) SINGLE LEVEL INHERITANCE
  // Base Class (Parent class)
  class Animal {
      String color;
      void eat() {
          System.out.println("Eats...");
      }
      void breath() {
          System.out.println("Breaths...");
      }
  }
  // Derived Class or SubClass (Child class)
  class Fish extends Animal {
      int fins;
      void swim() {
          System.out.println("Swims...");
      }
  }
  // (II) MULTI LEVEL INHERITANCE
  class Animal1 {
      String color;
      void eat() {
          System.out.println("Eats...");
      }
  }
  class Mammal extends Animal1 {
      int legs;
  }
  class Dog extends Mammal {
      String breed;
  }
  // (III) HIERARCHIAL INHERITANCE 
  class Animal2 {
      void breath() {
          System.out.println("Breaths...");
      }
      void eat() {
          System.out.println("Eats...");
      }
  }
  class Fish1 extends Animal2 {
      void swim() {
          System.out.println("Swims...");
      }
  }
  class Bird extends Animal2 {
      void fly() {
          System.out.println("Fly...");
      }
  }
  // (IV) HYBRID INHERITANCE
  class Animal3 {
      void eat() {
          System.out.println("Eats.");
      }
      void breath() {
          System.out.println("Breaths.");
      }
  }
  class Mammals extends Animal3 {
      void mammalEats() {
          System.out.println("Mammal Eats.");
      }
      void mammalSleep() {
          System.out.println("Mammal Sleeps.");
      }
  }
  class Human extends Mammals {
      void humanLegs() {
          System.out.println("Human have two legs.");
      }
  }
  class Lion extends Mammals {
      void lionRoars() {
          System.out.println("Lion are roars.");
      }
  }
  class Birds extends Animal3 {
      void birdFly() {
          System.out.println("Bird Flies.");
      }
  }
  class Peacock extends Birds {
      void peacockDance() {
          System.out.println("Peacock are Dances.");
      }
  }
  class Parrot extends Birds {
      void parrotColor() {
          System.out.println("Parrot have green color.");
      }
  }
  class Fishes extends Animal3 {
      void fishSwims() {
          System.out.println("Fishes are swims.");
      }
  }
  class Shark extends Fishes {
      void sharkFish() {
          System.out.println("Shark fish.");
      }
  }
  class Rohu extends Fishes {
      void rohuFish() {
          System.out.println("Rohu fish.");
      }
  }
  // (V) MULTIPLE INHERITANCE - It founds in C++ but It founds in java as Interfaces