Validating Field Content
A field validator is a Java class which prevents from changing to the next panel if one or more input field content is not valid during the installation. If the chosen validator reports some field content to be false, a messagebox is popped up with a defined (translated or untranslated content) and the user will be unable to continue to the next panel.
Validators are bound to particular fields, each field can have zero, one or more validators assigned in the user panel definition.
There are built-in validators available, and own, user-defined validator implementations can be used.