Java Collection Search getSingleElement(Collection collection)

Description

get Single Element

License

Apache License

Declaration

public static <T> T getSingleElement(Collection<T> collection) 

Method Source Code

//package com.java2s;
/* // w w w  .ja v a 2  s.co  m
 * Copyright 2014 Topeka Labs.
 *
 * 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.Collection;

public class Main {
    public static <T> T getSingleElement(Collection<T> collection) {
        isEmptyException(collection);
        return collection.iterator().next();
    }

    /**
     * This method throws an IllegalArgumentException if the given collection
     * is empty.
     * @param collection The collection to check.
     */
    public static void isEmptyException(Collection collection) {
        if (collection.isEmpty()) {
            throw new IllegalArgumentException("The given collection cannot be empty.");
        }
    }

    /**
     * This method throws an IllegalArgumentException if the given collection is
     * empty. The name of the collection is included in the exception message.
     * @param collection The collection to check.
     * @param collectionName The name of the collection.
     */
    public static void isEmptyException(Collection collection, String collectionName) {
        if (collection.isEmpty()) {
            throw new IllegalArgumentException("The given collection " + collectionName + " cannot be empty.");
        }
    }
}

Related

1. getSingle(Collection configs)
2. getSingleElement(Collection collection)
3. getSingleItem(Collection values)
4. getSingleValue(Iterable collection)
5. hasElements(Collection c)
6. hasElements(Collection c)