C#--Dictionary用法

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

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

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; 
    } 
 
 
} 

http://www.cnblogs.com/linlf03/archive/2011/12/09/2282574.html

http://www.cnblogs.com/ldp615/archive/2011/01/28/dictionary-extensions.html