คุณสมบัติ Stack.IsSynchronized ใน C# ใช้สำหรับตรวจสอบว่า Stack นั้นปลอดภัยเธรด (thread-safe) หรือไม่ โดยคืนค่า true หากปลอดภัยเธรด มิฉะนั้นคืนค่า false
ไวยากรณ์ (Syntax)
public virtual bool IsSynchronized { get; }
ตัวอย่างที่ 1: ตรวจสอบ Stack ปกติ
using System;
using System.Collections;
public class Demo
{
public static void Main()
{
Stack stack = new Stack();
stack.Push("Inspiron");
stack.Push("Alienware");
stack.Push("Projectors");
stack.Push("Monitors");
stack.Push("XPS");
stack.Push("Laptop");
stack.Push("Notebook");
Console.WriteLine("Stack elements...");
foreach (string val in stack)
{
Console.WriteLine(val);
}
Console.WriteLine("Count of elements = " + stack.Count);
Console.WriteLine("Element Speakers is in the stack? = " + stack.Contains("Speakers"));
stack.Push("Headphone");
stack.Push("Keyboard");
stack.Push("Earphone");
Console.WriteLine("\nStack elements...updated");
foreach (string val in stack)
{
Console.WriteLine(val);
}
Console.WriteLine("Count of elements (updated) = " + stack.Count);
Console.WriteLine("\nElement Alienware is in the stack? = " + stack.Contains("Alienware"));
Console.WriteLine("Is the Stack synchronized? = " + stack.IsSynchronized);
Stack stack2 = (Stack)stack.Clone();
Console.WriteLine("\nStack elements...cloned");
IEnumerator demoEnum = stack2.GetEnumerator();
while (demoEnum.MoveNext())
{
Console.WriteLine(demoEnum.Current);
}
Console.WriteLine("Count of elements (updated) = " + stack.Count);
}
}
ผลลัพธ์
Stack elements... Notebook Laptop XPS Monitors Projectors Alienware Inspiron Count of elements = 7 Element Speakers is in the stack? = False Stack elements...updated Earphone Keyboard Headphone Notebook Laptop XPS Monitors Projectors Alienware Inspiron Count of elements (updated) = 10 Element Alienware is in the stack? = True Is the Stack synchronized? = False Stack elements...cloned Earphone Keyboard Headphone Notebook Laptop XPS Monitors Projectors Alienware Inspiron Count of elements (updated) = 10
ตัวอย่างที่ 2: ทำให้ Stack ปลอดภัยเธรดด้วย Stack.Synchronized()
using System;
using System.Collections;
public class Demo
{
public static void Main()
{
Stack stack = new Stack();
stack.Push(150);
stack.Push(300);
stack.Push(500);
stack.Push(750);
stack.Push(1000);
stack.Push(1250);
stack.Push(1500);
stack.Push(2000);
stack.Push(2500);
Console.WriteLine("Stack elements...");
foreach (int val in stack)
{
Console.WriteLine(val);
}
Console.WriteLine("Count of elements = " + stack.Count);
Console.WriteLine("Element 750 is in the stack? = " + stack.Contains(750));
stack.Push(3000);
Console.WriteLine("\nStack elements...updated");
foreach (int val in stack)
{
Console.WriteLine(val);
}
Console.WriteLine("Count of elements (updated) = " + stack.Count);
Console.WriteLine("Element 5000 is in the stack? = " + stack.Contains(5000));
Stack stack2 = (Stack)stack.Clone();
Console.WriteLine("\nStack elements...cloned");
foreach (int val in stack2)
{
Console.WriteLine(val);
}
Console.Write("Count of elements (updated) = " + stack2.Count);
Console.WriteLine("\nIs the Stack synchronized? = " + stack.IsSynchronized);
Stack stack3 = Stack.Synchronized(stack);
Console.WriteLine("Is the Stack synchronized? = " + stack3.IsSynchronized);
}
}
ผลลัพธ์
Stack elements... 2500 2000 1500 1250 1000 750 500 300 150 Count of elements = 9 Element 750 is in the stack? = True Stack elements...updated 3000 2500 2000 1500 1250 1000 750 500 300 150 Count of elements (updated) = 10 Element 5000 is in the stack? = False Stack elements...cloned 3000 2500 2000 1500 1250 1000 750 500 300 150 Count of elements (updated) = 10 Is the Stack synchronized? = False Is the Stack synchronized? = True
ข้อสังเกตสำคัญ
- Stack ปกติ ไม่ได้ปลอดภัยเธรด (
IsSynchronized = false) - ใช้
Stack.Synchronized(stack)เพื่อสร้างวอร์ปเปอร์ที่ปลอดภัยเธรด - การ Clone Stack ไม่ทำให้ปลอดภัยเธรด — stack2 ยังคง IsSynchronized = false
- คุณสมบัติ
IsSynchronizedเป็น read-only - ใน .NET Core/.NET 5+ แนะนำให้ใช้
ConcurrentStack<T>จากSystem.Collections.Concurrentแทน — ประสิทธิภาพดีกว่าและออกแบบมาสำหรับคู่ขนาน
