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;
}
}
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