Java Collection Add addAllOrSame(Collection<T> collection, Collection<T> newElements)

Description

Adds to a collection all given new elements in a second collection, returning the second collection same instance if the first is null or empty.

License

Open Source License

Parameter

Parameter	Description
collection	a collection
newElements	new elements
T	the type of the elements in the collection.

Return

if collection null then newElements, else collection with newElements added to it.

Declaration

public static <T> Collection<T> addAllOrSame(Collection<T> collection, Collection<T> newElements)

Method Source Code

//package com.java2s;
/*/*  ww  w.  j  a v a  2  s  .c  o m*/
 * Copyright (c) 2013, SRI International
 * All rights reserved.
 * Licensed under the The BSD 3-Clause License;
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 * 
 * http://opensource.org/licenses/BSD-3-Clause
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of the aic-util nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS 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
 * COPYRIGHT HOLDER OR 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, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import java.util.Arrays;
import java.util.Collection;

import java.util.Iterator;

public class Main {
    /**
     * Adds to a collection all given new elements in a second collection, returning the second collection
     * same instance if the first is null or empty.
     * @param collection
     *        a collection
     * @param newElements
     *        new elements
     * @return if collection null then newElements, else collection with newElements added to it.
     * @param <T> the type of the elements in the collection.
     */
    public static <T> Collection<T> addAllOrSame(Collection<T> collection, Collection<T> newElements) {
        Collection<T> result;
        if (collection == null || collection.isEmpty()) {
            result = newElements;
        } else {
            collection.addAll(newElements);
            result = collection;
        }
        return result;
    }

    public static <T1> boolean isEmpty(Iterable<T1> i) {
        return !i.iterator().hasNext();
    }

    /**
     * Adds all elements of iterator's range to collection.
     * 
     * @param c
     *            the collection to add the iterator's range to.
     * @param i
     *            the iterator whose range is to be added to the given
     *            collection.
     * @return the given collection.
     * @param <T>
     *            the type of the elements given.
     * @param <C> the type of the collection
     */
    public static <T, C extends Collection<T>> C addAll(C c, Iterator<T> i) {
        while (i.hasNext()) {
            c.add(i.next());
        }
        return c;
    }

    /**
     * Construct an iterator of the given type ranging over provided elements.
     * 
     * @param elements
     *            the elements to construct the List from.
     * @return an iterator over the received arguments.
     * @param <T>
     *            the type of elements the iterator will range over.
     */
    public static <T> Iterator<T> iterator(T... elements) {
        return Arrays.asList(elements).iterator();
    }
}

Java Collection Add addAllOrSame(Collection collection, Collection newElements)