Here you can find the source of getAdditions(Collection
public static <T> Collection<T> getAdditions(Collection<T> source, Collection<T> target)
//package com.java2s; /******************************************************************************* * Copyright (c) 2013 Red Hat, Inc. /*from w ww .ja v a 2 s. co m*/ * Distributed under license by Red Hat, Inc. All rights reserved. * This program is made available under the terms of the * Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Red Hat, Inc. - initial API and implementation ******************************************************************************/ import java.util.ArrayList; import java.util.Collection; import java.util.List; public class Main { public static <T> Collection<T> getAdditions(Collection<T> source, Collection<T> target) { List<T> addedElements = new ArrayList<T>(); for (T element : target) { if (!source.contains(element)) { addedElements.add(element); } } return addedElements; } }