// generics/coffee/CoffeeSupplier.java

// (c)2016 MindView LLC: see Copyright.txt

// We make no guarantees that this code is fit for any purpose.

// Visit http://mindviewinc.com/Books/OnJava/ for more book information.

// {java generics.coffee.CoffeeSupplier}

package generics.coffee;

import java.util.*;

import java.util.function.*;

import java.util.stream.*;

public class CoffeeSupplier

implements Supplier<Coffee>, Iterable<Coffee> {

private Class<?>[] types = { Latte.class, Mocha.class,

Cappuccino.class, Americano.class, Breve.class, };

private static Random rand = new Random(47);

public CoffeeSupplier() {}

// For iteration:

private int size = 0;

public CoffeeSupplier(int sz) { size = sz; }

@Override

public Coffee get() {

try {

return (Coffee)

types[rand.nextInt(types.length)].newInstance();

// Report programmer errors at run time:

} catch(InstantiationException |

IllegalAccessException e) {

throw new RuntimeException(e);

}

}

class CoffeeIterator implements Iterator<Coffee> {

int count = size;

@Override

public boolean hasNext() { return count > 0; }

@Override

public Coffee next() {

count--;

return CoffeeSupplier.this.get();

}

@Override

public void remove() { // Not implemented

throw new UnsupportedOperationException();

}

}

@Override

public Iterator<Coffee> iterator() {

return new CoffeeIterator();

}

public static void main(String[] args) {

Stream.generate(new CoffeeSupplier())

.limit(5)

.forEach(System.out::println);

for(Coffee c : new CoffeeSupplier(5))

System.out.println(c);

}

}

/* Output:

Americano 0

Latte 1

Americano 2

Mocha 3

Mocha 4

Breve 5

Americano 6

Latte 7

Cappuccino 8

Cappuccino 9

*/