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

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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

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/// <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

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//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：

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public class Student

{

    public String Num { get; set; }

    public String Name { get; set; }

}

　　

 4 备注：Dictionary的扩展方法使用

 

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/// <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

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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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