据我所知，如果我宣布了一本字典，我可以调用myDict.Clear（）来重复使用。
现在，如果我将sb声明为StingBuilder obj。
StringBuilder sb = new StringBuilder();
如何重用某人？谢谢。
实际上我需要打印mainDict的所有可能条件。
像这样的某个sb表达式（包括在下面的代码中）
sb.AppendFormat("{0}/{1}/{2}/{3}, {4}", pair1.Key, pair2.Key, pair3.Key, pair4.Key, pair4.Value);
Console.WriteLine(sb.ToString());
如果我声明了很多StringBuilder objs，我仍然无法检测到有多少obj对我来说已经足够了。实际上mainDict非常复杂。上面的代码只是一种做法。感谢。
代码于1月4日更新。
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
class test
{
private static Dictionary<string, object> mainDict = new Dictionary<string, object>();
public static void Main()
{
Dictionary<string, object> aSubDict = new Dictionary<string,object>();
Dictionary<string, object> aSub1Dict = new Dictionary<string, object>();
Dictionary<string, object> aSub2Dict = new Dictionary<string, object>();
Dictionary<string, object> aSub3Dict = new Dictionary<string, object>();
Dictionary<string, object> aSub4Dict = new Dictionary<string, object>();
mainDict.Add("ADKey", aSubDict);
mainDict.Add("ASKey", "AValue");
aSubDict.Add("BDKey", aSub1Dict);
aSubDict.Add("BSKey", "BValue");
aSub1Dict.Add("CDKey", aSub2Dict);
aSub1Dict.Add("CSKey", "CValue");
aSub2Dict.Add("DDKey",aSub3Dict);
aSub2Dict.Add("DSKey", "DValue");
aSub3Dict.Add("EDKey", aSub4Dict);
aSub3Dict.Add("ESKey", "EValue");
aSub4Dict.Add("FKey", "FValue");
StringBuilder sb;
foreach (KeyValuePair<string, object> pair1 in mainDict)
// watch out for NullReferenceException
if (!ReferenceEquals(null, mainDict[pair1.Key]) && (mainDict[pair1.Key] is string))
{
Console.WriteLine("Key = {0}, Value = {1}", pair1.Key, pair1.Value);
sb = new StringBuilder();
sb.AppendFormat("{0}, {1}", pair1.Key, pair1.Value);
Console.WriteLine(sb.ToString());
}
// IDictionary is not the one from the Generics namespace, it is the one from the System.Collections namespace
else if (!ReferenceEquals(null, mainDict[pair1.Key]) && (mainDict[pair1.Key] is Dictionary<string, object>))
{
foreach (KeyValuePair<string, object> pair2 in (Dictionary<string, object>)pair1.Value)
if (!ReferenceEquals(null, ((Dictionary<string, object>)pair1.Value)[pair2.Key]) && (((Dictionary<string, object>)pair1.Value)[pair2.Key] is string))
{
Console.WriteLine("SubKey = {0}, Value = {1}", pair2.Key, pair2.Value);
sb = new StringBuilder();
sb.AppendFormat("{0}/{1}, {2}", pair1.Key, pair2.Key, pair2.Value);
Console.WriteLine(sb.ToString());
}
else if (!ReferenceEquals(null, ((Dictionary<string, object>)pair1.Value)[pair2.Key]) && (((Dictionary<string, object>)pair1.Value)[pair2.Key] is Dictionary<string, object>))
{
foreach (KeyValuePair<string, object> pair3 in (Dictionary<string, object>)pair2.Value)
if (!ReferenceEquals(null, ((Dictionary<string, object>)pair2.Value)[pair3.Key]) && (((Dictionary<string, object>)pair2.Value)[pair3.Key] is string))
{
Console.WriteLine("SubKey = {0}, Value = {1}", pair3.Key, pair3.Value);
sb = new StringBuilder();
sb.AppendFormat("{0}/{1}/{2}, {3}", pair1.Key, pair2.Key, pair3.Key, pair3.Value);
Console.WriteLine(sb.ToString());
}
else if (!ReferenceEquals(null, ((Dictionary<string, object>)pair2.Value)[pair3.Key]) && (((Dictionary<string, object>)pair2.Value)[pair3.Key] is Dictionary<string, object>))
{
foreach (KeyValuePair<string, object> pair4 in (Dictionary<string, object>)pair3.Value)
if (!ReferenceEquals(null, ((Dictionary<string, object>)pair3.Value)[pair4.Key]) && (((Dictionary<string, object>)pair3.Value)[pair4.Key] is string))
{
Console.WriteLine("SubKey = {0}, Value = {1}", pair4.Key, pair4.Value);
sb = new StringBuilder();
sb.AppendFormat("{0}/{1}/{2}/{3}, {4}", pair1.Key, pair2.Key, pair3.Key, pair4.Key, pair4.Value);
Console.WriteLine(sb.ToString());
}
else if (!ReferenceEquals(null, ((Dictionary<string, object>)pair3.Value)[pair4.Key]) && (((Dictionary<string, object>)pair3.Value)[pair4.Key] is Dictionary<string, object>))
{
foreach (KeyValuePair<string, object> pair5 in (Dictionary<string, object>)pair4.Value)
if (!ReferenceEquals(null, ((Dictionary<string, object>)pair4.Value)[pair5.Key]) && (((Dictionary<string, object>)pair4.Value)[pair5.Key] is string))
{
Console.WriteLine("SubKey = {0}, Value = {1}", pair5.Key, pair5.Value);
sb = new StringBuilder();
sb.AppendFormat("{0}/{1}/{2}/{3}/{4}, {5}", pair1.Key, pair2.Key, pair3.Key, pair4.Key, pair5.Key, pair5.Value);
Console.WriteLine(sb.ToString());
}
else if (!ReferenceEquals(null, ((Dictionary<string, object>)pair4.Value)[pair5.Key]) && (((Dictionary<string, object>)pair4.Value)[pair5.Key] is Dictionary<string, object>))
{
foreach (KeyValuePair<string, object> pair6 in (Dictionary<string, object>)pair5.Value)
if (!ReferenceEquals(null, ((Dictionary<string, object>)pair5.Value)[pair6.Key]) && (((Dictionary<string, object>)pair5.Value)[pair6.Key] is string))
{
Console.WriteLine("SubKey = {0}, Value = {1}", pair6.Key, pair6.Value);
sb = new StringBuilder();
sb.AppendFormat("{0}/{1}/{2}/{3}/{4}/{5}, {6}", pair1.Key, pair2.Key, pair3.Key, pair4.Key, pair5.Key, pair6.Key, pair6.Value);
Console.WriteLine(sb.ToString());
}
else if (!ReferenceEquals(null, ((Dictionary<string, object>)pair5.Value)[pair6.Key]) && (((Dictionary<string, object>)pair5.Value)[pair6.Key] is Dictionary<string, object>))
{
Console.WriteLine("sub Dict Found");
}
}
}
}
}
}
}
}
像这样输出
SubKey = FKey, Value = FValue
ADKey/BDKey/CDKey/DDKey/EDKey/FKey, FValue
SubKey = ESKey, Value = EValue
ADKey/BDKey/CDKey/DDKey/ESKey, EValue
SubKey = DSKey, Value = DValue
ADKey/BDKey/CDKey/DSKey, DValue
SubKey = CSKey, Value = CValue
ADKey/BDKey/CSKey, CValue
SubKey = BSKey, Value = BValue
ADKey/BSKey, BValue
Key = ASKey, Value = AValue
ASKey, AValue
答案 0 :(得分：21)
您可以将Length设置为0.在.NET 4.0中，也有Clear()方法。作为Clear州的文档：
Clear是一种方便的方法 相当于设置长度 当前实例的属性为0 （零）。
所以这不是什么大问题：）
我个人会避免这样做，除非你真的需要 - 我通常只是创建一个新的StringBuilder。在我看来，这更容易理解 - 它更清楚你不再需要来自前一个对象的任何。
您有什么特别的理由要重用该对象吗？如果是出于性能原因，您是否测量了性能并发现这是一个瓶颈？我想如果你有一个容量非常大的实例，并且你想避免再次分配它，那么它可能会很重要......但这对我来说感觉有点边缘。
（所有这些也适用于字典，顺便说一句。我记不清上次我清除字典了。）
答案 1 :(得分：0)
我认为应该创建一个新的StringBuilder对象，而不是重用现有的StringBuilder对象。