Asynchronous Programming – Task.CompletedTask and Task.FromResult

By | 18/01/2023

In this post, we will see how and when using Task.CompletedTask and Task.FromResult.

WHEN
We can use both of them when, we need to return a Task object from a method that don’t have any async operations.

HOW
Task.CompletedTask
When we need to return a Task:

[CORE.CS]

namespace TestTaskCompleted
{
    public class Core
    {
        public async Task PrintResult(int maxValue)
        {
            int result = 0;

            for (int i = 1; i < maxValue; i++)
            {
                result = result + 10;
            }

            Console.WriteLine($"The result is {result}");

            await Task.CompletedTask;
        }
    }
}


[PROGRAM.CS]

using TestTaskCompleted;

Core objCore = new Core();

await objCore.PrintResult(12);


If we run the application, this will be the result:


Task.FromResult
When we need to return a Task<T>:

[CORE.CS]

namespace TestTaskCompleted
{
    public class Core
    {
        public async Task<int> SumAsync(int maxValue)
        {
            int result = 0;

            for (int i = 1; i < maxValue; i++)
            {
                result = result + 10;
            }

            return await Task.FromResult<int>(result);
        }
    }
}


[PROGRAM.CS]

using TestTaskCompleted;

Core objCore = new Core();

var result = await objCore.SumAsync(12);

Console.WriteLine($"The result is: {result}");


If we run the application, this will be the result:



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