Set Union，获取包含所提供集合中所有项的集合。

/*

 * Copyright Terracotta, Inc.

 *

 * 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.

 */

//package com.nowjava;
/**
时 代 J     a    v  a - nowjava.com
**/


import java.util.HashSet;


import java.util.List;


import java.util.Set;


public class Main {

    public static void main(String[] argv) throws Exception {

        List sets = java.util.Arrays.asList("asdf", "nowjava.com");

        System.out.println(unionSets(sets));

    }


    /**

     * Gets a {@code Set} containing all of the entries from the sets provided.

     *

     * @param sets the {@code Set} instances to combine

     *

     * @return a new {@code Set} containing all of the elements

     */

    private static Set<String> unionSets(final List<Set<String>> sets) {

        final Set<