Find a value of one of the given types in the given Collection, searching the Collection for a value of the first type, then searching for a value of the second type, etc. - CSharp System.Collections.Generic

CSharp examples for System.Collections.Generic:ICollection

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Description

Find a value of one of the given types in the given Collection, searching the Collection for a value of the first type, then searching for a value of the second type, etc.

Demo Code

/*//  w  ww.j a  v  a2 s .  c  o  m
 * Copyright ? 2002-2011 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.
 */
using System.Reflection;
using System.Collections;
using System;

public class Main{
        /// <summary>
        /// Find a value of one of the given types in the given Collection, 
        /// searching the Collection for a value of the first type, then
        /// searching for a value of the second type, etc.
        /// </summary>
        /// <param name="collection">The collection to search.</param>
        /// <param name="types">The types to look for, in prioritized order.</param>
        /// <returns>a value of the given types found, or <code>null</code> if none</returns>
        /// <exception cref="ArgumentException">If more than one value of the given type is found</exception>        
        public static object FindValueOfType(ICollection collection, Type[] types)
        {
            if (IsEmpty(collection) || ObjectUtils.IsEmpty(types))
            {
                return null;
            }
            foreach (Type type in types)
            {
                object val = FindValueOfType(collection, type);
                if (val != null)
                {
                    return val;
                }
            }
            return null;
        }
        /// <summary>
        /// Finds a value of the given type in the given collection.
        /// </summary>
        /// <param name="collection">The collection to search.</param>
        /// <param name="type">The type to look for.</param>
        /// <returns>a value of the given type found, or null if none.</returns>
        /// <exception cref="ArgumentException">If more than one value of the given type is found</exception>
        public static object FindValueOfType(ICollection collection, Type type)
        {
            if (IsEmpty(collection))
            {
                return null;
            }
            Type typeToUse = (type != null ? type : typeof(object));
            object val = null;
            foreach (object obj in collection)
            {
                if (typeToUse.IsAssignableFrom(obj.GetType()))
                {
                    if (val != null)
                    {
                        throw new ArgumentException("More than one value of type[" + typeToUse.Name + "] found.");
                    }
                    val = obj;
                }
            }
            return val;
        }
        /// <summary>
        /// Determines whether the specified dictionary is null empty.
        /// </summary>
        /// <param name="dictionary">The dictionary to check.</param>
        /// <returns>
        ///    <c>true</c> if the specified dictionary is empty or null; otherwise, <c>false</c>.
        /// </returns>
        public static bool IsEmpty(IDictionary dictionary)
        {
            return (dictionary == null || dictionary.Count == 0);
        }
        /// <summary>
        /// Determines whether the specified collection is null or empty.
        /// </summary>
        /// <param name="collection">The collection to check.</param>
        /// <returns>
        ///    <c>true</c> if the specified collection is empty or null; otherwise, <c>false</c>.
        /// </returns>
        public static bool IsEmpty(ICollection collection)
        {
            return (collection == null || collection.Count == 0);
        }
        /// <summary>
        /// Determines whether the specified collection is null or empty.
        /// </summary>
        /// <param name="enumerable">The collection to check.</param>
        /// <returns>
        ///    <c>true</c> if the specified collection is empty or null; otherwise, <c>false</c>.
        /// </returns>
        public static bool IsEmpty(IEnumerable enumerable)
        {
            if (enumerable == null)
                return true;

            if (enumerable is ICollection)
            {
                return (0 == ((ICollection)enumerable).Count);
            }

            IEnumerator it = enumerable.GetEnumerator();
            if (!it.MoveNext())
            {
                return true;
            }
            return false;
        }
}

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