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; }} |
