private void OnGenerateExerciseClicked(object sender, RoutedEventArgs e) { int.TryParse(ExerciseNumberTextBox.Text, out int exerNum); if (exerNum < 0 || exerNum > 300) { MessageBox.Show("Please select a number between 0 and 300"); return; } IExercise exercise = ExerGeneratorFactory.GetInstance().GetExerciseGenerator(SelectedExerciseType); if (exercise == null) { return; } string exers = exercise.GenerateExercises(exerNum); ResultTextBlock.Text = exers; }