Here you can find the source of add_all(Collection extends T> target, Collection extends T> source)
@SuppressWarnings("unchecked") public static <T> Collection<? extends T> add_all(Collection<? extends T> target, Collection<? extends T> source)
//package com.java2s; //License from project: Open Source License import java.util.Collection; public class Main { @SuppressWarnings("unchecked") public static <T> Collection<? extends T> add_all(Collection<? extends T> target, Collection<? extends T> source) { ((Collection<T>) target).addAll(source); return target; }/*from www .ja v a2 s. co m*/ public static <T> void addAll(Collection<T> target, Iterable<? extends T> source) { for (T e : source) target.add(e); } public static <T> void addAll(Collection<T> collection, T[] array) { for (int i = 0; i < array.length; ++i) collection.add(array[i]); } }