// onjava/Suppliers.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// A utility to use with Suppliers
package onjava;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Suppliers {
 // Create a collection and fill it:
 public static <T, C extends Collection<T>> C
 create(Supplier<C> factory, Supplier<T> gen, int n) {
 return Stream.generate(gen)
 .limit(n)
 .collect(factory, C::add, C::addAll);
 }
 // Fill an existing collection:
 public static <T, C extends Collection<T>>
 C fill(C coll, Supplier<T> gen, int n) {
 Stream.generate(gen)
 .limit(n)
 .forEach(coll::add);
 return coll;
 }
 // Use an unbound method reference to
 // produce a more general method:
 public static <H, A> H fill(H holder,
 BiConsumer<H, A> adder, Supplier<A> gen, int n) {
 Stream.generate(gen)
 .limit(n)
 .forEach(a -> adder.accept(holder, a));
 return holder;
 }
}