Java Collection Intersect intersect(Collection... collections)

License

Parameter

Return

Declaration

public static <A> Set<A> intersect(Collection<A>... collections) 

Method Source Code

//package com.java2s;
/*******************************************************************************
 * Copyright (c) 2016 Pablo Pavon-Marino.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser Public License v2.1
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/lgpl.html
 *
 * Contributors:/*from   ww  w  .j  av a 2 s .  c o  m*/
 *     Pablo Pavon-Marino - Jose-Luis Izquierdo-Zaragoza, up to version 0.3.1
 *     Pablo Pavon-Marino - from version 0.4.0 onwards
 ******************************************************************************/

import java.util.*;

public class Main {
    /**
     * Returns the intersection set of a series of input collections. There is no order guarantee.
     *
     * @param <A> Key type
     * @param collections Series of input collections
     * @return Intersection set of input collections
     */
    public static <A> Set<A> intersect(Collection<A>... collections) {
        if (collections.length == 0)
            return new LinkedHashSet<A>();

        Set<A> intersectionSet = new LinkedHashSet<A>();
        intersectionSet.addAll(collections[0]);

        for (int i = 1; i < collections.length; i++) {
            intersectionSet.retainAll(collections[i]);
        }

        return intersectionSet;
    }
}

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