Java Collection Find findValueOfType(Collection collection, Class type)

Description

Find a single value of the given type in the given Collection.

License

Apache License

Parameter

Parameter	Description
collection	the Collection to search
type	the type to look for

Return

a value of the given type found if there is a clear match, or null if none or more than one such value found

Declaration

@SuppressWarnings("unchecked")
public static <T> T findValueOfType(Collection<?> collection, Class<T> type) 

Method Source Code

//package com.java2s;
/*/* www .  j  ava 2s  . c  om*/
 * Copyright 2002-2015 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.Collection;

public class Main {
    /**
     * Find a single value of the given type in the given Collection.
     * @param collection the Collection to search
     * @param type the type to look for
     * @return a value of the given type found if there is a clear match,
     * or {@code null} if none or more than one such value found
     */
    @SuppressWarnings("unchecked")
    public static <T> T findValueOfType(Collection<?> collection, Class<T> type) {
        if (isEmpty(collection)) {
            return null;
        }
        T value = null;
        for (Object element : collection) {
            if (type == null || type.isInstance(element)) {
                if (value != null) {
                    // More than one value found... no clear single value.
                    return null;
                }
                value = (T) element;
            }
        }
        return value;
    }

    /**
     * Return {@code true} if the supplied Collection is {@code null} or empty.
     * Otherwise, return {@code false}.
     * @param collection the Collection to check
     * @return whether the given Collection is empty
     */
    public static boolean isEmpty(Collection<?> collection) {
        return (collection == null || collection.isEmpty());
    }
}

Related

1. findCommonElementType(Collection collection)
2. findMax(Collection vals)
3. findMax(Collection vals)
4. findMax(Iterable collection)
5. findValueOfType(Collection collection, Class type)
6. isAnyIncludedIn(Collection findAnyOfThese, Collection inThisCollection)