Stack.Synchronized() Method in C#

Last Updated : 11 Jul, 2025

This method(comes under System.Collections Namespace) is used to return a synchronized (thread safe) wrapper for the Stack. To guarantee the thread safety of the Stack, all operations must be done through this wrapper. Syntax:

public static System.Collections.Stack Synchronized (System.Collections.Stack stack);

Return Value: It returns synchronized wrapper around the Stack. Exception: This method will give ArgumentNullException if the stack is null. Below programs illustrate the use of above-discussed method: Example 1:

csharp

// C# code to illustrate the
// Stack.Synchronized() Method
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a Stack
        Stack myStack = new Stack();

        // Inserting the elements into the Stack
        myStack.Push("Geeks");
        myStack.Push("Geeks Classes");
        myStack.Push("Noida");
        myStack.Push("Data Structures");
        myStack.Push("GeeksforGeeks");

        // Creates a synchronized
        // wrapper around the Stack
        Stack st = Stack.Synchronized(myStack);

        // Displays the synchronization
        // status of both Stack
        Console.WriteLine("myStack is {0}.", myStack.IsSynchronized ?
                                "Synchronized" : "Not Synchronized");

        Console.WriteLine("st is {0}.", st.IsSynchronized ? 
                      "Synchronized" : "Not Synchronized");
    }
}

Output:

myStack is Not Synchronized.
st is Synchronized.

Example 2:

csharp

// C# code to illustrate the
// Stack.Synchronized() Method
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating a Stack
        Stack myStack = new Stack();

        // Inserting the elements into the Stack
        myStack.Push("C");
        myStack.Push("C++");
        myStack.Push("Java");
        myStack.Push("C#");
        myStack.Push("Python");

        // it will give error as
        // the parameter is null
        Stack sq = Stack.Synchronized(null);
    }
}