Java Collection Intersect hasIntersection(final Collection a, final Collection b)

Description

Returns true iff the given Collection s.

License

LGPL

Parameter

Parameter	Description
a	the first collection considered for intersection
b	the second collection considered for intersection

Return

true if the given s. have any elements in common.

Declaration

public static boolean hasIntersection(final Collection a,
        final Collection b) 

Method Source Code

//package com.java2s;
/**/*from  w ww  .j a  v a 2 s  .  co m*/
 * Provides <tt>Collection</tt> utilities not otherwise provided by Jakarta Commons.  All methods
 * are static.  There is no need to instantiate this class.<p>
 *
 * @version $Id: OcCollectionUtils.java 138070 2012-01-10 19:46:08Z sbrown $
 * @author Stephen L. Reed
 *
 * <p>Copyright 2001 Cycorp, Inc., license is open source GNU LGPL.
 * <p><a href="http://www.opencyc.org/license.txt">the license</a>
 * <p><a href="http://www.opencyc.org">www.opencyc.org</a>
 * <p><a href="http://www.sourceforge.net/projects/opencyc">OpenCyc at SourceForge</a>
 * <p>
 * THIS SOFTWARE AND KNOWLEDGE BASE CONTENT ARE PROVIDED ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OPENCYC
 * ORGANIZATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE AND KNOWLEDGE
 * BASE CONTENT, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.util.*;

public class Main {
    /**
     * Returns <tt>true</tt> iff the given {@link Collection}s.
     * have any elements in common.  Performs HashSet search for
     * larger collections.
     *
     * @param a the first collection considered for intersection
     * @param b the second collection considered for intersection
     * @return <tt>true</tt> if the given {@link Collection}s.
     * have any elements in common.
     */
    public static boolean hasIntersection(final Collection a,
            final Collection b) {
        if (a.size() < 50 && b.size() < 50) {
            Iterator it = a.iterator();
            while (it.hasNext())
                if (b.contains(it.next()))
                    return true;
        } else if (a.size() < b.size()) {
            HashSet bSet = new HashSet(b);
            Iterator it = a.iterator();
            while (it.hasNext())
                if (bSet.contains(it.next()))
                    return true;
        } else {
            HashSet aSet = new HashSet(a);
            Iterator it = b.iterator();
            while (it.hasNext())
                if (aSet.contains(it.next()))
                    return true;
        }
        return false;
    }
}

Related

1. getIntersection(Collection collection1, Collection collection2)
2. hasIntersection(Collection s1, Collection s2)
3. hasIntersection(Collection a, Collection b)
4. hasIntersection(Collection c1, Collection c2)
5. hasIntersection(Collection col1, Collection col2)
6. intersect(Collection c1, Collection c2)
7. intersect(Collection c1, Collection c2)
8. intersect(Collection collection, Collection otherCollection)
9. intersect(Collection... collections)