Returns a new ArrayList with the same contents as source, except for the case that source is nil or empty, in which source itself is returned. - Java Collection Framework

Java examples for Collection Framework:Array Element Filter

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Description

Returns a new ArrayList with the same contents as source, except for the case that source is nil or empty, in which source itself is returned.

Demo Code

/*******************************************************************************
 * Copyright (c) 2010 SAP AG.//www . j  av a  2 s. c  o  m
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Emil Simeonov - initial API and implementation.
 *    Dimitar Donchev - initial API and implementation.
 *    Dimitar Tenev - initial API and implementation.
 *    Nevena Manova - initial API and implementation.
 *    Georgi Konstantinov - initial API and implementation.
 *    Jakob Spies - initial API and implementation.
 *******************************************************************************/
//package com.java2s;
import java.util.ArrayList;
import java.util.Collection;

public class Main {
    public static void main(String[] argv) {
        Collection source = java.util.Arrays.asList("asdf", "java2s.com");
        System.out.println(duplicate(source));
    }

    /**
     * Returns a new {@link ArrayList} with the same contents as <code>source</code>,
     * except for the case that <code>source</code> is nil or empty, in which <code>source</code>
     * itself is returned.
     * @param <T> element type
     * @param source the {@link Collection} to clone
     * @return a new {@link ArrayList} with the same contents as <code>source</code>,
     *    except for the case that <code>source</code> is nil or empty, in which <code>source</code>
     *    itself is returned
     */
    public static <T> Collection<T> duplicate(Collection<T> source) {
        final Collection<T> result;

        if (source == null || source.isEmpty()) {
            result = source;
        } else {
            result = new ArrayList<T>(source.size());
            result.addAll(source);
        }

        return result;
    }
}

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