Here you can find the source of removed(Collection
public static List<String> removed(Collection<String> old, Collection<String> nu)
//package com.java2s; /*// w w w.ja va2s .c om * Copyright 2011-2015 Hippo B.V. (http://www.onehippo.com) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.util.ArrayList; import java.util.Collection; import java.util.List; public class Main { public static List<String> removed(Collection<String> old, Collection<String> nu) { List<String> removed = null; for (String s : old) { if (!nu.contains(s)) { if (removed == null) { removed = new ArrayList<String>(old.size()); } removed.add(s); } } return removed; } }