Why this shows no output
class Main { public static void main(String[] args) { Animal dog = new Dog(); Animal cat = new Cat(); dog.swim(); cat.swim(); dog.play(); cat.play(); } } interface Swimmer { void swim(); } interface Player { void play(); } //implement the Swimmer and the Player interfaces abstract class Animal implements Swimmer , Player { public abstract void swim(); public abstract void play(); } class Dog extends Animal { //Override the swim() and the play() methods public void swim(){ System.out.println("1"); } public void play(){ System.out.println("2"); } } class Cat extends Animal { //Override the swim() and the play() methods public void swim(){ System.out.println("3"); } public void play(){ System.out.println("4"); } } }