Vaadin8: Validation without binding possible

Vaadin 6 / 7 / 8
1

How can I validate or show a validation error in a form if I don’t want to use binding?

Thanks,
Roland

2

I think the recommended approach is to do validation as part of a value-change event listener. You can still use a validator like StringLengthValidator, but you have to manually invoke it on value change.

3

…and if I find an error do I call setComponentError()? The argument is an ErrorMessage. How do I construct an ErrorMessage?

4 
new UserError("message to be shown");
5

Excellent, thanks!