Android : Toast in onPostExecute() in android

I am trying to post a toast in OnPostExecture in an Async.

Here is the what I have done but it doesn't log and it is not toasting.

protected class sendDetails extends AsyncTask<Context, Integer, Boolean>
{

    @Override
    protected Boolean doInBackground(Context... params) 
    {
        try 
        {
            Thread.sleep(1000);
        }
        catch (InterruptedException e) 
        {
        }

        sendEmail();
        return true;
    }

    @Override
    protected void onPostExecute(Boolean result) 
    {
        runOnUiThread(new Runnable() 
        {
            public void run() 
            {
                Toast.makeText(mContext, "Email Succesfully Sent...", Toast.LENGTH_SHORT).show();
            }
        });
    }

    @Override
    protected void onPreExecute() 
    {
        super.onPreExecute();
        finish();
    }
}

I also tried the following:

Declaring Context:
private Context mContext;

//Calling the Async
new sendDetails(mContext).execute();

protected class sendDetails extends AsyncTask<Context, Integer, Boolean>
{

    public sendDetails(final Context context) 
    {
        mContext = context;
    }

    @Override
    protected Boolean doInBackground(Context... params) 
    {
        try 
        {
            Thread.sleep(1000);
        }
        catch (InterruptedException e) 
        {
        }

        sendEmail();
        return true;
    }

    @Override
    protected void onPostExecute(Boolean result) 
    {
        runOnUiThread(new Runnable() 
        {
            public void run() 
            {
                Toast.makeText(mContext, "Email Succesfully Sent...", Toast.LENGTH_SHORT).show();
            }
        });
    }

    @Override
    protected void onPreExecute() 
    {
        super.onPreExecute();
        finish();
    }
}

Both didn't work. Can somebody help me fix this?

Thanks!