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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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本文转自Work Hard Work Smart博客园博客，原文链接：http://www.cnblogs.com/linlf03/archive/2011/12/09/2282574.html，如需转载请自行联系原作者