Convert code Java to c#

Design Patterns
1

Hello, How i can use this code on C#:

public SignUpDialogBox() {
usernameTextBox.addEventHandler(this::controlChanged);
passwordTextBox.addEventHandler(this::controlChanged);
agreeToTermsCheckBox.addEventHandler(this::controlChanged);
}

private void controlChanged() {
    signUpButton.setEnabled(isFormValid());
}

Thanks

2

I changed to inline class but it is more code. Maybe with c# event handler and delegates it is easier

public class ArticlesDialogBox
{
        public class ArticleObserver : IObserver
        {
            ArticlesDialogBox articlesDialogBox;
            public ArticleObserver(ArticlesDialogBox articlesDialogBox)
            {
                this.articlesDialogBox = articlesDialogBox;
            }
            public void update() => articlesDialogBox.articleSelected();
        }

        public class TitleObserver : IObserver
        {
            ArticlesDialogBox articlesDialogBox;
            public TitleObserver(ArticlesDialogBox articlesDialogBox)
            {
                this.articlesDialogBox = articlesDialogBox;
            }
            public void update() => articlesDialogBox.titleChanged();
        }

        public ArticlesDialogBox()
        {
            articlesListBox.attach(new ArticleObserver(this));
            titleTextBox.attach(new TitleObserver(this));

        }