多态练习（声音模拟器）

public class Application {public static void main(String[] args) {Simulator simulator = new Simulator();simulator.playSound(new Dog());simulator.playSound(new Cat());}}

public abstract class Animal {abstract void cry();abstract String getAnimalName();}

public class Cat extends Animal{void cry(){System.out.println("喵喵喵");}    String getAnimalName(){    return "咪呜";}}

public class Dog extends Animal{void cry(){System.out.println("汪汪汪");} String getAnimalName(){return "旺财";}}

public class Simulator {void playSound(Animal animal){System.out.println(animal.getAnimalName()+"的叫声：");animal.cry();}}