Java Iterable Item single(Iterable source)

Description

Returns the single element in the collection or throws.

License

Apache License

Declaration

public static <T> T single(Iterable<? extends T> source) 

Method Source Code

//package com.java2s;
/*/* w ww  .j a  v a2s .c  om*/
 * Copyright 2011 the original author or authors.
 *
 * 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 {
    /**
     * Returns the single element in the collection or throws.
     */
    public static <T> T single(Iterable<? extends T> source) {
        Iterator<? extends T> iterator = source.iterator();
        if (!iterator.hasNext()) {
            throw new NoSuchElementException("Expecting collection with single element, got none.");
        }
        T element = iterator.next();
        if (iterator.hasNext()) {
            throw new IllegalArgumentException("Expecting collection with single element, got multiple.");
        }
        return element;
    }
}

Related

1. iterableContains(Iterable i, E match)
2. maxes(Iterable elements)
3. prefix(final Iterable lines, final String prefix)
4. print(Iterable coll, String sep)
5. reverse(Iterable values)
6. toArray(Iterable elements)