如何调用异步任务 <bool> 方法？

Question

This is the async function i have created, here am getting error while claaing this function on buttion click.

public async Task<bool> Login(string UserName, string Password)
    {
        try
        {
            ParseUser User = await ParseUser.LogInAsync(UserName, Password);
            System.Windows.Forms.MessageBox.Show(User.ObjectId);
            var currentUser = ParseUser.CurrentUser;
            return true;
        }
        catch (Exception ex)
        {
            System.Windows.Forms.MessageBox.Show(ex.Message);
            return false;
        }           
    }

its getting error while calling.

private void btnLogin_Click(object sender, EventArgs e)
    {
        if (Login(txtUserName.Text,txtPassword.Text))
        {
            MessageBox.Show("Login Success");                       
        }            
    }

Answer 1

You need to asynchronously wait for the Login method like this:

private async void btnLogin_Click(object sender, EventArgs e)
{
    if (await Login(txtUserName.Text,txtPassword.Text))
    {
        MessageBox.Show("Login Success");                       
    }            
}

Now, this event handler is asynchronous (by using the async keyword) and it asynchronously waits for the Login method (by using the await keyword).

Please note that in general, it is not recommended to have async void methods. However, one exception for this rule are event handlers. So this code is fine.

Answer 2

You need to asynchronously wait for the method as shown below:

 private async void btnLogin_Click(object sender, EventArgs e) {
 var task = Login(txtUserName.Text, txtPassword.Text)
 var result = await task;
 if (result) {
  MessageBox.Show("Login Success");
 }
}