C# | Creating a synchronized (thread-safe) wrapper for a SortedList object

Last Updated : 11 Jul, 2025
SortedList.Synchronized(SortedList) Method is used to get the synchronized (thread-safe) wrapper for a SortedList object. Syntax:
public static System.Collections.SortedList Synchronized (System.Collections.SortedList list);
Here, list is the name of the SortedList object which is to be synchronized. Exception: This method will throw ArgumentNullException if the list is null. Below programs illustrate the use of above-discussed method: Example 1: CSharp 
// C# code to create a synchronized
// (thread-safe) wrapper for a
// SortedList object
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an SortedList
        SortedList mySortedList = new SortedList();

        // Adding elements to SortedList
        mySortedList.Add("1", "one");
        mySortedList.Add("2", "two");
        mySortedList.Add("3", "three");
        mySortedList.Add("4", "four");
        mySortedList.Add("5", "five");

        // Creating a synchronized wrapper
        // around the SortedList.
        SortedList mySortedList_1 = 
            SortedList.Synchronized(mySortedList);

        // --------- Using IsSynchronized Property

        // print the status of both SortedList
        Console.WriteLine("mySortedList SortedList is {0}.",
              mySortedList.IsSynchronized ? "synchronized" : 
                                         "not synchronized");

        Console.WriteLine("mySortedList_1 SortedList is {0}.",
              mySortedList_1.IsSynchronized ? "synchronized" : 
                                          "not synchronized");
    }
}
Output: 
mySortedList SortedList is not synchronized.
mySortedList_1 SortedList is synchronized.
Example 2: CSharp 
// C# code to create a synchronized
// (thread-safe) wrapper for a
// SortedList object
using System;
using System.Collections;

class GFG {

    // Driver code
    public static void Main()
    {

        // Creating an SortedList
        SortedList mySortedList = new SortedList();

        // Adding elements in SortedList 
        mylist.Add("4", "Even"); 
        mylist.Add("9", "Odd"); 
        mylist.Add("5", "Odd and Prime"); 
        mylist.Add("2", "Even and Prime"); 

        // it will give runtime error as
        // table parameter can't be null
        SortedList my2 = SortedList.Synchronized(null);
    }
}
Runtime Error:
Unhandled Exception: System.ArgumentNullException: Value cannot be null. Parameter name: list
Note: For the thread safety of a SortedList object, all operations must be done through this wrapper only. Reference:
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