获得一个通用的字典价值的关键? [英] Getting key of value of a generic Dictionary?
本文介绍了获得一个通用的字典价值的关键?的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
可以很容易地获得从.NET 2.0通用词典一键的值:
词典< INT,字符串>希腊=新字典< INT,字符串>();
greek.Add(1,阿尔法);
greek.Add(2Beta版);
字符串secondGreek =希腊语[2]; // Beta版
但有一个简单的方法来获取值的关键?
INT [] betaKeys = greek.WhatDoIPutHere(Beta版); //期待单2
解决方案
好了,这里的多个双向版本:
使用系统;
使用System.Collections.Generic;
使用System.Text;
类BiDictionary< TFirst,TSecond>
{
IDictionary的< TFirst,IList的< TSecond>> firstToSecond =新字典< TFirst,IList的< TSecond>>();
IDictionary的< TSecond,IList的< TFirst>> secondToFirst =新字典< TSecond,IList的< TFirst>>();
私有静态的IList< TFirst> EmptyFirstList =新TFirst [0];
私有静态的IList< TSecond> EmptySecondList =新TSecond [0];
公共无效添加(TFirst第一,TSecond秒)
{
IList的< TFirst>首创;
IList的< TSecond>秒;
如果(!firstToSecond.TryGetValue(第一,走出秒))
{
秒=新的名单,其中,TSecond>();
firstToSecond [首页] =秒;
}
如果(!secondToFirst.TryGetValue(第二,出创举))
{
首创=新的名单,其中,TFirst>();
secondToFirst [二] =首创;
}
seconds.Add(第二);
firsts.Add(第一);
}
//注意潜在的不确定性使用索引(例如映射从int到int)
//因此,方法以及...
公众的IList< TSecond>这[TFirst首页]
{
{返回GetByFirst(第一); }
}
公众的IList< TFirst>这[TSecond秒]
{
{返回GetBySecond(第二); }
}
公众的IList< TSecond> GetByFirst(TFirst第一)
{
IList的< TSecond>清单;
如果(!firstToSecond.TryGetValue(第一,出名单))
{
返回EmptySecondList;
}
返回新的List< TSecond>(名单); //创建理智副本
}
公众的IList< TFirst> GetBySecond(TSecond秒)
{
IList的< TFirst>清单;
如果(!secondToFirst.TryGetValue(第二,出名单))
{
返回EmptyFirstList;
}
返回新的List< TFirst>(名单); //创建理智副本
}
}
类测试
{
静态无效的主要()
{
BiDictionary< INT,字符串>希腊=新BiDictionary< INT,字符串>();
greek.Add(1,阿尔法);
greek.Add(2Beta版);
greek.Add(5,贝塔);
ShowEntries(希腊语,阿尔法);
ShowEntries(希腊语,贝塔);
ShowEntries(希腊语,伽玛);
}
静态无效ShowEntries(BiDictionary< INT,字符串>字典,字符串键)
{
IList的< INT>值=字典[关键];
StringBuilder的建设者=新的StringBuilder();
的foreach(中值int值)
{
如果(builder.Length!= 0)
{
builder.Append(,);
}
builder.Append(值);
}
Console.WriteLine({0}:[{1}]键,建设者);
}
}
It's easy to get the value of a key from a .Net 2.0 generic Dictionary:
Dictionary<int, string> greek = new Dictionary<int, string>();
greek.Add(1, "Alpha");
greek.Add(2, "Beta");
string secondGreek = greek[2]; // Beta
But is there a simple way to get the key of a value?
int[] betaKeys = greek.WhatDoIPutHere("Beta"); // expecting single 2
解决方案
Okay, here's the multiple bidirectional version:
using System;
using System.Collections.Generic;
using System.Text;
class BiDictionary<TFirst, TSecond>
{
IDictionary<TFirst, IList<TSecond>> firstToSecond = new Dictionary<TFirst, IList<TSecond>>();
IDictionary<TSecond, IList<TFirst>> secondToFirst = new Dictionary<TSecond, IList<TFirst>>();
private static IList<TFirst> EmptyFirstList = new TFirst[0];
private static IList<TSecond> EmptySecondList = new TSecond[0];
public void Add(TFirst first, TSecond second)
{
IList<TFirst> firsts;
IList<TSecond> seconds;
if (!firstToSecond.TryGetValue(first, out seconds))
{
seconds = new List<TSecond>();
firstToSecond[first] = seconds;
}
if (!secondToFirst.TryGetValue(second, out firsts))
{
firsts = new List<TFirst>();
secondToFirst[second] = firsts;
}
seconds.Add(second);
firsts.Add(first);
}
// Note potential ambiguity using indexers (e.g. mapping from int to int)
// Hence the methods as well...
public IList<TSecond> this[TFirst first]
{
get { return GetByFirst(first); }
}
public IList<TFirst> this[TSecond second]
{
get { return GetBySecond(second); }
}
public IList<TSecond> GetByFirst(TFirst first)
{
IList<TSecond> list;
if (!firstToSecond.TryGetValue(first, out list))
{
return EmptySecondList;
}
return new List<TSecond>(list); // Create a copy for sanity
}
public IList<TFirst> GetBySecond(TSecond second)
{
IList<TFirst> list;
if (!secondToFirst.TryGetValue(second, out list))
{
return EmptyFirstList;
}
return new List<TFirst>(list); // Create a copy for sanity
}
}
class Test
{
static void Main()
{
BiDictionary<int, string> greek = new BiDictionary<int, string>();
greek.Add(1, "Alpha");
greek.Add(2, "Beta");
greek.Add(5, "Beta");
ShowEntries(greek, "Alpha");
ShowEntries(greek, "Beta");
ShowEntries(greek, "Gamma");
}
static void ShowEntries(BiDictionary<int, string> dict, string key)
{
IList<int> values = dict[key];
StringBuilder builder = new StringBuilder();
foreach (int value in values)
{
if (builder.Length != 0)
{
builder.Append(", ");
}
builder.Append(value);
}
Console.WriteLine("{0}: [{1}]", key, builder);
}
}
这篇关于获得一个通用的字典价值的关键?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文