Dictionary<k,v>键值对的使用美高梅4858官方网站

作者:编程技术

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Dictionary键值对
{

    class Program
    {
        static void Main(string[] args)
        {
            DicSample1();
            DicSample2();
            DicSample3();
            DicSample4();

            Console.Read();
        }

        //1、用法1: 常规用
        //  增加键值对之前需要判断是否存在该键,如果已经存在该键而且不判断,将抛出异常。所以这样每次都要进行判断,很麻烦,在备注里使用了一个扩展方法
        public static void DicSample1()
        {
            Dictionary<String, String> pList = new Dictionary<String, String>();
            try
            {
                if (pList.ContainsKey("Item1") == false)
                {
                    pList.Add("Item1", "ZheJiang");
                }
                if (pList.ContainsKey("Item2") == false)
                {
                    pList.Add("Item2", "ShangHai");
                }
                else
                {
                    pList["Item2"] = "ShangHai";
                }
                if (pList.ContainsKey("Item3") == false)
                {
                    pList.Add("Item3", "BeiJiang");
                }

            }
            catch (System.Exception e)
            {
                Console.WriteLine("Error: {0}", e.Message);
            }


            //判断是否存在相应的key并显示
            if (pList.ContainsKey("Item1"))
            {
                Console.WriteLine("Output: "   pList["Item1"]);
            }

            //遍历Key
            foreach (var key in pList.Keys)
            {
                Console.WriteLine("Output Key: {0}", key);
            }

            //遍历Value
            foreach (String value in pList.Values)
            {
                Console.WriteLine("Output Value: {0}", value);
            }
            //遍历Key和Value
            foreach (var dic in pList)
            {
                Console.WriteLine("Output Key : {0}, Value : {1} ", dic.Key, dic.Value);
            }
        }

        //2、用法2:Dictionary的Value为一个数组
        /// <summary>
        /// Dictionary的Value为一个数组
        /// </summary>
        public static void DicSample2()
        {
            Dictionary<String, String[]> dic = new Dictionary<String, String[]>();
            String[] ZheJiang = { "Huzhou", "HangZhou", "TaiZhou" };
            String[] ShangHai = { "Budong", "Buxi" };
            dic.Add("ZJ", ZheJiang);
            dic.Add("SH", ShangHai);
            Console.WriteLine("Output :"   dic["ZJ"][0]);
        }

        //3、用法3: Dictionary的Value为一个类
        //Dictionary的Value为一个类
        public static void DicSample3()
        {
            Dictionary<String, Student> stuList = new Dictionary<String, Student>();
            Student stu = null;
            for (int i = 0; i < 3; i  )
            {
                stu = new Student();
                stu.Name = i.ToString();
                stu.Name = "StuName"   i.ToString();
                stuList.Add(i.ToString(), stu);
            }

            foreach (var student in stuList)
            {
                Console.WriteLine("Output : Key {0}, Num : {1}, Name {2}", student.Key, student.Value.Name, student.Value.Name);
            }
        }

        //4 备注:Dictionary的扩展方法使用
        /// <summary>
        /// Dictionary的扩展方法使用
        /// </summary>
        public static void DicSample4()
        {
            //1)普通调用
            Dictionary<int, String> dict = new Dictionary<int, String>();
            DictionaryExtensionMethodClass.TryAdd(dict, 1, "ZhangSan");
            DictionaryExtensionMethodClass.TryAdd(dict, 2, "WangWu");
            DictionaryExtensionMethodClass.AddOrPeplace(dict, 3, "WangWu");
            DictionaryExtensionMethodClass.AddOrPeplace(dict, 3, "ZhangWu");
            DictionaryExtensionMethodClass.TryAdd(dict, 2, "LiSi");

            //2)TryAdd 和 AddOrReplace 这两个方法具有较强自我描述能力,用起来很省心,而且也简单:
            dict.AddOrPeplace(20, "Orange");
            dict.TryAdd(21, "Banana");
            dict.TryAdd(22, "apple");

            //3)像Linq或jQuery一样连起来写   
            dict.TryAdd(10, "Bob")
                .TryAdd(11, "Tom")
                .AddOrPeplace(12, "Jom");

            //4) 获取值
            String F = "Ba";
            dict.TryGetValue(31, out F);
            Console.WriteLine("F : {0}", F);

            foreach (var dic in dict)
            {
                Console.WriteLine("Output : Key : {0}, Value : {1}", dic.Key, dic.Value);
            }
            //5)下面是使用GetValue获取值
            var v1 = dict.GetValue(111, null);
            var v2 = dict.GetValue(10, "abc");

            //6)批量添加
            var dict1 = new Dictionary<int, int>();
            dict1.AddOrPeplace(3, 3);
            dict1.AddOrPeplace(5, 5);

            var dict2 = new Dictionary<int, int>();
            dict2.AddOrPeplace(1, 1);
            dict2.AddOrPeplace(4, 4);
            dict2.AddRange(dict1, false);
        }       
    }

    //Student类:
    public class Student
    {
        public String Num { get; set; }
        public String Name { get; set; }
    }

    //扩展方法所在的类
    public static class DictionaryExtensionMethodClass
    {
        /// <summary>
        /// 尝试将键和值添加到字典中:如果不存在,才添加;存在,不添加也不抛导常
        /// </summary>
        public static Dictionary<TKey, TValue> TryAdd<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, TValue value)
        {
            if (dict.ContainsKey(key) == false)
                dict.Add(key, value);
            return dict;
        }

        /// <summary>
        /// 将键和值添加或替换到字典中:如果不存在,则添加;存在,则替换
        /// </summary>
        public static Dictionary<TKey, TValue> AddOrPeplace<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, TValue value)
        {
            dict[key] = value;
            return dict;
        }

        /// <summary>
        /// 获取与指定的键相关联的值,如果没有则返回输入的默认值
        /// </summary>
        public static TValue GetValue<TKey, TValue>(this Dictionary<TKey, TValue> dict, TKey key, TValue defaultValue)
        {
            return dict.ContainsKey(key) ? dict[key] : defaultValue;
        }

        /// <summary>
        /// 向字典中批量添加键值对
        /// </summary>
        /// <param name="replaceExisted">如果已存在,是否替换</param>
        public static Dictionary<TKey, TValue> AddRange<TKey, TValue>(this Dictionary<TKey, TValue> dict, IEnumerable<KeyValuePair<TKey, TValue>> values, bool replaceExisted)
        {
            foreach (var item in values)
            {
                if (dict.ContainsKey(item.Key) == false || replaceExisted)
                    dict[item.Key] = item.Value;
            }
            return dict;
        }
    }
}

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