Java Collection Merge merge(Collection... elems)

Description

Merge few collections in one.

License

Apache License

Parameter

Parameter	Description
elems	the array of collections of type T
T	the collections type and result list type.

Return

the list of all merged values.

Declaration

public static <T> List<T> merge(Collection<T>... elems) 

Method Source Code

//package com.java2s;
/*//from   w  w  w  . j  av a 2 s  .c  o  m
 * Copyright 2008-2010 Ruslan Khmelyuk.
 *
 * Licensed 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.*;

public class Main {
    /**
     * Merge few collections in one.
     * The result list is of <code>ArrayList</code> type.
     * If parameter is <code>null</code>, then result list is empty.
     *
     * @param elems the array of collections of type T
     * @param <T>   the collections type and result list type.
     * @return the list of all merged values.
     */
    public static <T> List<T> merge(Collection<T>... elems) {
        List<T> resultList = arrayList();
        if (elems != null) {
            for (Collection<T> eachCollection : elems) {
                resultList.addAll(eachCollection);
            }
        }
        return resultList;
    }

    /**
     * Returns the list that can be changes.
     * The list contains elements given as parameters.
     *
     * @param elems the elements to add to the list.
     * @return the array list with elements.
     */
    public static <T> List<T> arrayList(T... elems) {
        return new ArrayList<T>(listOf(elems));
    }

    /**
     * Returns the list of elements given as parameters.
     *
     * @param elems the elements to add to the list.
     * @return the list with elements.
     */
    public static <T> List<T> listOf(T... elems) {
        return java.util.Arrays.asList(elems);
    }
}

Related

1. merge(Collection dest, Collection src)
2. merge(Collection splits)
3. merge(Collection strings, char separator)
4. merge(Collection... collections)
5. merge(Collection... collections)
6. merge(final Collection values)
7. merge(J just, Collection justs)
8. mergeArrayIntoCollection(T[] array, Collection collection)
9. mergeCollection( final Collection col1, final Collection col2)