ภาพรวม
ListDictionary มีคุณสมบัติ SyncRoot ใช้กับ lock เพื่อให้การเข้าถึงเป็น thread-safe
ตัวอย่างที่ 1: ตรวจสอบคุณสมบัติและล็อก SyncRoot
using System;
using System.Collections;
using System.Collections.Specialized;
public class Demo
{
public static void Main()
{
ListDictionary dict = new ListDictionary();
dict.Add("1", "SUV");
dict.Add("2", "Sedan");
dict.Add("3", "Utility Vehicle");
dict.Add("4", "Compact Car");
dict.Add("5", "SUV");
dict.Add("6", "Sedan");
dict.Add("7", "Utility Vehicle");
dict.Add("8", "Compact Car");
dict.Add("9", "Crossover");
dict.Add("10", "Electric Car");
Console.WriteLine("ListDictionary elements...");
foreach (DictionaryEntry d in dict)
{
Console.WriteLine(d.Key + " " + d.Value);
}
Console.WriteLine("\nIs the ListDictionary having fixed size? = " + dict.IsFixedSize);
Console.WriteLine("If ListDictionary read-only? = " + dict.IsReadOnly);
Console.WriteLine("Is ListDictionary synchronized = " + dict.IsSynchronized);
Console.WriteLine("The ListDictionary has the key K? = " + dict.Contains("K"));
Console.WriteLine("The ListDictionary has the key 9? = " + dict.Contains("9"));
Console.WriteLine("\nSynchronize access...");
lock (dict.SyncRoot)
{
foreach (DictionaryEntry d in dict)
{
Console.WriteLine(d.Key + " " + d.Value);
}
}
}
}
ผลลัพธ์
ListDictionary elements... 1 SUV 2 Sedan 3 Utility Vehicle 4 Compact Car 5 SUV 6 Sedan 7 Utility Vehicle 8 Compact Car 9 Crossover 10 Electric Car Is the ListDictionary having fixed size? = False If ListDictionary read-only? = False Is ListDictionary synchronized = False The ListDictionary has the key K? = False The ListDictionary has the key 9? = True Synchronize access... 1 SUV 2 Sedan 3 Utility Vehicle 4 Compact Car 5 SUV 6 Sedan 7 Utility Vehicle 8 Compact Car 9 Crossover 10 Electric Car
ตัวอย่างที่ 2: ล็อก SyncRoot แบบง่าย
using System;
using System.Collections;
using System.Collections.Specialized;
public class Demo
{
public static void Main()
{
ListDictionary dict = new ListDictionary();
dict.Add("A", "Books");
dict.Add("B", "Electronics");
dict.Add("C", "Appliances");
dict.Add("D", "Pet Supplies");
dict.Add("E", "Clothing");
dict.Add("F", "Footwear");
Console.WriteLine("Synchronize access...");
lock (dict.SyncRoot)
{
foreach (DictionaryEntry d in dict)
{
Console.WriteLine(d.Key + " " + d.Value);
}
}
}
}
ผลลัพธ์
Synchronize access... A Books B Electronics C Appliances D Pet Supplies E Clothing F Footwear
สรุป
- ใช้
lock(dict.SyncRoot)ครอบการอ่าน/เขียน ListDictionary IsSynchronizedคืน false เสมอ ต้องจัดการล็อกเอง- ListDictionary เหมาะกับข้อมูลน้อย (< 10) ใหญ่กว่านั้นควรใช้ HybridDictionary หรือ Dictionary
