Java Collection First getUnionSize(Collection firstCollection, Collection secondCollection)

Description

Given two Collections, return the size of their union

License

Apache License

Parameter

Parameter	Description
firstCollection	The first collection. <code>null</code> is allowed.
secondCollection	The second collection. <code>null</code> is allowed.

Declaration

public static <E> int getUnionSize(Collection<? extends E> firstCollection,
        Collection<? extends E> secondCollection) 

Method Source Code

//package com.java2s;
/*//from ww w  .  j  av  a 2 s . c  o m
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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.Collection;

public class Main {
    /**
     * Given two Collections, return the size of their union
     * @param firstCollection The first collection.  <code>null</code> is allowed.
     * @param secondCollection The second collection.  <code>null</code> is allowed.
     * @return
     */
    public static <E> int getUnionSize(Collection<? extends E> firstCollection,
            Collection<? extends E> secondCollection) {
        int firstSize = (firstCollection != null) ? firstCollection.size() : 0;

        int secondSize = (secondCollection != null) ? secondCollection.size() : 0;

        if (firstSize == 0)
            return secondSize;

        if (secondSize == 0)
            return firstSize;

        // determine the size of the union by iterating over the smaller collection
        int size;
        Collection<? extends E> iteratingCollection;
        Collection<? extends E> baseCollection;

        if (firstSize >= secondSize) {
            baseCollection = firstCollection;
            iteratingCollection = secondCollection;
            size = firstSize;
        } else {
            baseCollection = secondCollection;
            iteratingCollection = firstCollection;
            size = secondSize;
        }

        for (E currValue : iteratingCollection) {
            if (!baseCollection.contains(currValue)) {
                size++;
            }
        }

        return size;
    }
}

Related

1. getFirstN(Collection objects, int n)
2. getFirstNonNull(Collection c)
3. getFirstNotNullValue(final Collection collection)
4. getFirstOrNull(final Collection collection)
5. getFirstSortedItem( Collection items, T defaultValue)
6. intersect(Collection firstSet, Collection secondSet)
7. nullSafeFirstElement(Collection collection)
8. removeFirst(Collection collection, int numToRemove)
9. removeFirst(Collection c)