Java List Sum sum(final List list1, final List list2)

Description

Returns the sum of the given lists.

License

Open Source License

Parameter

Parameter	Description
list1	the first list
list2	the second list

Exception

Parameter	Description
NullPointerException	if either list is null

Return

a new list containing the sum of those lists

Declaration

public static List sum(final List list1, final List list2) 

Method Source Code

//package com.java2s;
/*/* w  w  w .  j a v  a  2s  . c  o  m*/
 * Copyright (c) 2007-2016 AREasy Runtime
 *
 * This library, AREasy Runtime and API for BMC Remedy AR System, is free software ("Licensed Software");
 * you can redistribute it and/or modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either version 2.1 of the License,
 * or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 * including but not limited to, the implied warranty of MERCHANTABILITY, NONINFRINGEMENT,
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
 */

import java.util.*;

public class Main {
    /**
     * Returns the sum of the given lists.  This is their intersection
     * subtracted from their union.
     *
     * @param list1 the first list
     * @param list2 the second list
     * @return a new list containing the sum of those lists
     * @throws NullPointerException if either list is null
     */
    public static List sum(final List list1, final List list2) {
        return subtract(union(list1, list2), intersection(list1, list2));
    }

    /**
     * Subtracts all elements in the second list from the first list,
     * placing the results in a new list.
     * <p/>
     * This differs from {@link List#removeAll(Collection)} in that
     * cardinality is respected; if <Code>list1</Code> contains two
     * occurrences of <Code>null</Code> and <Code>list2</Code> only
     * contains one occurrence, then the returned list will still contain
     * one occurrence.
     *
     * @param list1 the list to subtract from
     * @param list2 the list to subtract
     * @return a new list containing the results
     * @throws NullPointerException if either list is null
     */
    public static List subtract(final List list1, final List list2) {
        final ArrayList result = new ArrayList(list1);
        final Iterator iterator = list2.iterator();

        while (iterator.hasNext()) {
            result.remove(iterator.next());
        }

        return result;
    }

    /**
     * Returns a new list containing the second list appended to the
     * first list.  The {@link List#addAll(Collection)} operation is
     * used to append the two given lists into a new list.
     *
     * @param list1 the first list
     * @param list2 the second list
     * @return a new list containing the union of those lists
     * @throws NullPointerException if either list is null
     */
    public static List union(final List list1, final List list2) {
        final ArrayList result = new ArrayList(list1);

        result.addAll(list2);

        return result;
    }

    /**
     * Returns a new list containing all elements that are contained in
     * both given lists.
     *
     * @param list1 the first list
     * @param list2 the second list
     * @return the intersection of those two lists
     * @throws NullPointerException if either list is null
     */
    public static List intersection(final List list1, final List list2) {
        final ArrayList result = new ArrayList();
        final Iterator iterator = list2.iterator();

        while (iterator.hasNext()) {
            final Object o = iterator.next();

            if (list1.contains(o))
                result.add(o);
        }

        return result;
    }
}

Related

1. getSum(List values)
2. getSum(List longList)
3. getSumOfInts(List ints)
4. getSumOfPositiveDoubles(List scores)
5. removeOne(List summary, int start)
6. sum(final List list)
7. sum(final List list)
8. sum(int[] list)
9. sum(List list)