// stack demo with type derivation based on the article from http://www.25hoursaday.com/CsharpVsJava.html#same

import java.util.Stack;

interface Mammal {

// default speak() implementation

default void speak() {

System.out.println("*Generic mammal sound*");

}

}

class Dog implements Mammal {

// Dog provides its own speak() implementation

public void speak() {

System.out.println("Woof! Woof!");

}

}

class Cat implements Mammal {

// Cat provides its own speak() implementation

public void speak() {

System.out.println("Meow! Meow!");

}

}

class MuteKoala implements Mammal {

// mute koala is mute is no speak() implementation :(

}

class StackDemo2 {

// wildcard with upper bound to capture all Mammal-derived stacks

// (keyword 'extends' used for classes and interfaces!)

public static void annoyNeighbors(Stack<? extends Mammal> pets) {

while (!pets.empty()) {

Mammal animal = pets.pop();

animal.speak();

}

}

public static void main(String[] args) {

// stack of different mammals

Stack<Mammal> pets = new Stack<Mammal>();

// add some animals to the stack (both push() and add() allowed)

pets.add(new Dog());

pets.add(new Cat());

pets.add(new MuteKoala());

// make some animal noise!

System.out.println("Your pets are annoying the neighbors:");

annoyNeighbors(pets);

System.out.println("Your neighbors are furious...");

}

}