Here you can find the source of toLongArray(final List
public static long[] toLongArray(final List<Long> list)
//package com.java2s; //License from project: LGPL import java.util.*; public class Main { public static long[] toLongArray(final List<Long> list) { long[] array = new long[list.size()]; for (int i = 0; i < list.size(); i++) { array[i] = list.get(i);/* ww w.j av a2s . com*/ } return array; } public static int size(final Object[] array) { return null != array ? array.length : 0; } public static int size(final Collection collection) { return null != collection ? collection.size() : 0; } public static int size(final Map map) { return null != map ? map.size() : 0; } public static <T> T get(T[] array, int index) { if (array.length < index + 1) { return null; } return array[index]; } public static <T> T get(final T[] array, final int index, final T defaultValue) { if (array.length < index + 1) { return defaultValue; } final T result = array[index]; return null != result ? result : defaultValue; // array[index]; } public static <T> T get(final Collection<T> collection, final int index) { if (collection.size() < index + 1) { return null; } int i = 0; for (T item : collection) { if (i == index) { return item; } i++; } return null; } }