get Sole Element from Collection - Java java.util

Java examples for java.util:Collection Element

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Description

get Sole Element from Collection

Demo Code

/*/*from ww  w  .ja  v  a 2s  . c  o m*/
 * The MIT License
 *
 * Copyright (c) 2010 The Broad Institute
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
//package com.java2s;
import java.util.*;

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

    public static <T> T getSoleElement(final Collection<T> items) {
        if (items.size() != 1)
            throw new IllegalArgumentException(String.format(
                    "Expected a single element in %s, but found %s.",
                    items, items.size()));
        return items.iterator().next();
    }
}

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