Java Collection Concatenate concat(boolean removeDuplicates, Collection firstCollection, Collection... collections)

Description

concat

License

Apache License

Declaration

public static <E> List<E> concat(boolean removeDuplicates, Collection<? extends E> firstCollection,
            Collection<?>... collections) 

Method Source Code

//package com.java2s;
/**/*from w ww . j  ava 2s .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.ArrayList;

import java.util.Collection;

import java.util.List;

public class Main {
    public static <E> List<E> concat(boolean removeDuplicates, Collection<? extends E> firstCollection,
            Collection<?>... collections) {
        final List<E> result;
        if (removeDuplicates) {
            result = new ArrayList<E>();
            addElements(removeDuplicates, result, firstCollection);
        } else {
            result = new ArrayList<E>(firstCollection);
        }
        for (Collection<?> collection : collections) {
            @SuppressWarnings("unchecked")
            Collection<? extends E> elems = (Collection<? extends E>) collection;
            addElements(removeDuplicates, result, elems);
        }
        return result;
    }

    private static <E> void addElements(boolean removeDuplicates, final List<E> result,
            Collection<? extends E> elements) {
        for (E item : elements) {
            if (removeDuplicates) {
                if (!result.contains(item)) {
                    result.add(item);
                }
            } else {
                result.add(item);
            }
        }
    }
}

Related

1. concat(Collection> classes, String separator)
2. concat(Collection collection, String delimiter)
3. concat(Collection c)
4. concat(Collection items)