Maxim Kirilov’s answer is incomplete. It doesn’t check for blank/empty Strings.
I’ve faced the same issue before, and I realized that in addition to using @NonNull and @Builder from Lombok, overload the constructor with a private access modifier, where you can perform the validations. Something like this:
private Person(final String firstName, final String lastName) {
if(StringUtils.isBlank(firstName)) {
throw new IllegalArgumentException("First name can't be blank/empty/null");
}
if(StringUtils.isBlank(lastName)) {
throw new IllegalArgumentException("Last name can't be blank/empty/null");
}
this.firstName = firstName;
this.lastName = lastName;
}
Also, throwing IllegalArgumentException makes more sense (instead of NPE) when String has blank, empty or null values.