C# Dictionary用法总结

C# Dictionary用法总结

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);
            }
        }

　　

Student类：

    public class Student
    {
        public String Num { get; set; }
        public String Name { get; set; }
    }

　　

 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);
         }

　　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;
        }


    }

参考资料

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