// Another level of validation. No point in moving to the "Book fields"
// if there is no ISBN
private void BookFields_Enter(object sender, EventArgs e)
{
if (ValidateBook.ISBN(textBoxISBN.Text))
{
UpdateStatus("Please fill in a Title, Author, Rating & year published");
}
else
{
textBoxISBN.HighlightFocus();
UpdateErrorStatus("Please supply a postive non-zero whole number ISBN first");
}
}
// Validate the textboxes. If validated, enable the respected buttons.
private void ValidateBoxes(object sender, EventArgs e)
{
bool isbnValid = ValidateBook.ISBN(textBoxISBN.Text);
buttonAddBook.Enabled = isbnValid &&
ValidateBook.Title(textBoxTitle.Text) &&
ValidateBook.Author(textBoxAuthor.Text) &&
ValidateBook.Rating(textBoxRating.Text) &&
ValidateBook.PubYear(textBoxPubYear.Text);
// buttonGetAllISBN is enabled by Adding a book and disabled by
// removing all books from the BST.
buttonFindBook.Enabled = isbnValid & books.HasEntries;
buttonRemoveBook.Enabled = isbnValid & books.HasEntries;
}