©TCP-tryJAVA

import java.util.*;

class LandAnimal { public void crying() { System.out.println("육지동물"); } }
class Cat extends LandAnimal { public void crying() { System.out.println("냐옹냐옹"); } }
class Dog extends LandAnimal { public void crying() { System.out.println("멍멍"); } }
class Sparrow { public void crying() { System.out.println("짹짹"); } } 

class AnimalList<T extends LandAnimal> {
	ArrayList<T> al = new ArrayList<T>();
	
	void add(T animal) { al.add(animal); }
	T get(int index) { return al.get(index); }
	boolean remove(T animal) { return al.remove(animal); }
	int size() { return al.size(); }
}

public class prog {
	public static void main(String[] args) {
		AnimalList<LandAnimal> landAnimal = new AnimalList<>();	// Java SE 7부터 생략가능함.
		
		landAnimal.add(new LandAnimal());
		landAnimal.add(new Cat());
		landAnimal.add(new Dog());
		// landAnimal.add(new Sparrow());	// 오류가 발생함.
		
		for (int i = 0; i < landAnimal.size() ; i++) {
			landAnimal.get(i).crying();
		}
	}
}