Wait for abstract function to finish c#

Question

I have two class (CLASS1 and CLASS2), from CLASS1 i call an abstract method and i need wait to end of it and show a message "End Process...", how can i solve this?

CLASS-1:

public abstract partial class CLASS1 : Form
{
    public CLASS1()
    {
        Console.WriteLine("Start Process ABSMethod1");
        ABSMethod1("var1", "var2");
        Console.WriteLine("End Process ABSMethod1");

        Console.WriteLine("Start Process ABSMethod2");
        ABSMethod2(1, 2);
        Console.WriteLine("End Process ABSMethod2");
    }

    protected abstract void ABSMethod1(String var1, String var2);
    protected abstract void ABSMethod2(int var1, int var2);
}

CLASS-2:

class CLASS2: CLASS1
{
    protected override void ABSMethod1(String var1, String var2)
    {
        if (var1 == "test")
        {
            Task.Factory.StartNew(() =>
            {
                Parallel.ForEach<clssmt>(items, item =>
                {
                    /* ... */
                });
            });
        }
        //if i use Task.Wait() freezes UI.
    }

    protected override void ABSMethod2(int var1, int var2)
    {
        Task.Factory.StartNew(() =>
        {
            Parallel.ForEach<clssmt>(items, item =>
            {
                /* ... */
            });
        });
    }
}

I solve this problem using protected virtual async Task and await, but i'm not sure if it is the best solution. And if i use this solution, the message "End Procces" is shown little before that Task is finished.

Answer 1

i need wait to end of it and show a message "End Process...", how can i solve this?

You expose those executed Task's to the caller. You also don't invoke them via your constructor, but via an initialization method:

protected abstract Task FirstMethodAsync(string var1, string var2);
protected abstract Task SecondMethodAsync(int var1, int var2);

public async Task InitializeAsync()
{
     Console.WriteLine("Start Process ABSMethod1");
     await FirstMethodAsync("var1", "var2");
     Console.WriteLine("End Process ABSMethod1");

     Console.WriteLine("Start Process ABSMethod2");
     await SecondMethodAsync(1, 2);
     Console.WriteLine("End Process ABSMethod2");
}