How can I bean-validate on a char?

Question

I just found that @Pattern might work (only) with CharSequences.

How can I validate a single char?

//@Pattern(regex = "[YN]") // @@?
private char someYn; // 'Y' or 'N'

Will it blend?

Using an AttributeConverter is not an option.

Oh, is a single char also a CharSequence?

@Pattern(regexp = "^[Y|N]{1}$", message ="Must be Y or N") try this.You cannot use @Pattern for Character variable, You will get exception — GauravRai1512, Nov 14 '18 at 01:31
@GauravRai1512 Is `{1}` part necessary? I'm not asking about the `regex`, anyway, thanks. — Jin Kwon, Nov 14 '18 at 01:36
@GauravRai1512 That is not true. `{1}` is completely redundant. — VGR, Nov 14 '18 at 01:43

Mykhailo Moskura · Accepted Answer · 2018-11-14T02:05:02.643

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You can write your own ConstraintValidator:

https://docs.oracle.com/javaee/7/api/javax/validation/ConstraintValidator.html

Where you can provide annotation and validation type for which you can define your logic And then you can annotate your field with your custom annotation

Here is link with steps how to make it :

https://dzone.com/articles/create-your-own-constraint-with-bean-validation-20

As per javax validation documentation :

@Pattern(regex=, flag=) String.

Additionally supported by HV: any sub-type of CharSequence.

Checks if the annotated string matches the regular expression regex considering the given flag

So actually with Character using @Pattern you will get the error

Thanks

edited Nov 14 '18 at 02:05

answered Nov 14 '18 at 01:42

Mykhailo Moskura

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Sir, request to confirm, `@Pattern` doesn't work for `char`? Thanks. – Jin Kwon Nov 14 '18 at 01:46
You can refer to post https://stackoverflow.com/questions/12599069/hibernate-validator-for-chars – Mykhailo Moskura Nov 14 '18 at 01:53
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Yes as per javax.validation says we cannot use Character – Mykhailo Moskura Nov 14 '18 at 02:04

How can I bean-validate on a char?

1 Answers1