How to validate number string as digit with hibernate?

Question

Which annotations would I have to use for Hibernate Validation to validate a String to apply to the following:

//should always have trimmed length = 6, only digits, only positive number @NotEmpty @Size(min = 6, max = 6) public String getNumber {     return number.trim(); } 

How can I apply digit validation? Would I just use @Digits(fraction = 0, integer = 6) here?

Answer 1

You could replace all your constraints with a single @Pattern(regexp="[\\d]{6}"). This would imply a string of length six where each character is a digit.

Answer 2

You can also create your own hibernate validation annotation.
In the example below I created a validation annotation with name EnsureNumber. Fields with this annotation will validate with the isValid method of the EnsureNumberValidator class.

@Constraint(validatedBy = EnsureNumberValidator.class) @Target({ ElementType.FIELD }) @Retention(RetentionPolicy.RUNTIME) public @interface EnsureNumber {      String message() default "{PasswordMatch}";      Class<?>[] groups() default {};      Class<? extends Payload>[] payload() default {};      boolean decimal() default false;  }  public class EnsureNumberValidator implements ConstraintValidator<EnsureNumber, Object> {     private EnsureNumber ensureNumber;      @Override     public void initialize(EnsureNumber constraintAnnotation) {         this.ensureNumber = constraintAnnotation;     }      @Override     public boolean isValid(Object value, ConstraintValidatorContext context) {         // Check the state of the Adminstrator.         if (value == null) {             return false;         }          // Initialize it.         String regex = ensureNumber.decimal() ? "-?[0-9][0-9\\.\\,]*" : "-?[0-9]+";         String data = String.valueOf(value);         return data.matches(regex);     }  } 

You can use it like this,

@NotEmpty @Size(min = 6, max = 6) @EnsureNumber private String number1;  @NotEmpty @Size(min = 6, max = 6) @EnsureNumber(message = "Field number2 is not valid.") private String number2;  @NotEmpty @Size(min = 6, max = 6) @EnsureNumber(decimal = true, message = "Field number is not valid.") private String number3;