com.jdroid.java.collections.Iterables Maven / Gradle / Ivy

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package com.jdroid.java.collections;

import java.util.Collection;

public class Iterables {
	
	/**
	 * Returns the number of elements in {@code iterable}.
	 * 
	 * @param iterable The {@link Iterable}
	 * @return The {@link Iterable} size
	 */
	public static int size(Iterable iterable) {
		return (iterable instanceof Collection) ? ((Collection)iterable).size()
				: Iterators.size(iterable.iterator());
	}
	
	/**
	 * Copies an iterable's elements into an array.
	 * 
	 * @param iterable the iterable to copy
	 * @param type the type of the elements
	 * @return a newly-allocated array into which all the elements of the iterable have been copied
	 */
	public static  T[] toArray(Iterable iterable, Class type) {
		Collection collection = toCollection(iterable);
		T[] array = ObjectArrays.newArray(type, collection.size());
		return collection.toArray(array);
	}
	
	/**
	 * Converts an iterable into a collection. If the iterable is already a collection, it is returned. Otherwise, an
	 * {@link java.util.ArrayList} is created with the contents of the iterable in the same iteration order.
	 */
	private static  Collection toCollection(Iterable iterable) {
		return (iterable instanceof Collection) ? (Collection)iterable : Lists.newArrayList(iterable.iterator());
	}
	
}