org.yarnandtail.andhow.api

Interface Validator<T>

Type Parameters:

T - The data type the validator can validate.

All Known Implementing Classes:

BaseValidator, BigDecValidator, BigDecValidator.GreaterThan, BigDecValidator.GreaterThanOrEqualTo, BigDecValidator.LessThan, BigDecValidator.LessThanOrEqualTo, DblValidator, DblValidator.GreaterThan, DblValidator.GreaterThanOrEqualTo, DblValidator.LessThan, DblValidator.LessThanOrEqualTo, IntValidator, IntValidator.GreaterThan, IntValidator.GreaterThanOrEqualTo, IntValidator.LessThan, IntValidator.LessThanOrEqualTo, LngValidator, LngValidator.GreaterThan, LngValidator.GreaterThanOrEqualTo, LngValidator.LessThan, LngValidator.LessThanOrEqualTo, LocalDateTimeValidator, LocalDateTimeValidator.After, LocalDateTimeValidator.Before, LocalDateTimeValidator.SameTimeOrAfter, LocalDateTimeValidator.SameTimeOrBefore, StringValidator.EndsWith, StringValidator.OneOf, StringValidator.OneOfIgnoringCase, StringValidator.Regex, StringValidator.StartsWith

public interface Validator<T>

A single validation rule and rule metadata for a Property value.

Method Summary

Modifier and Type	Method and Description
String	getInvalidMessage(T value) A user message explaining why the value is not valid if it fails this validation rule.
String	getInvalidSpecificationMessage() If the specification itself is invalid (such as a bad regex string), this will build a message describing the problem to the user.
String	getTheValueMustDescription() Get a description of the validation rule.
boolean	isSpecificationValid() Returns true if the validation criteria itself is valid.
boolean	isValid(T value) Determines if the non-null value is valid according to the rule this validator enforces.

Method Detail

isValid

boolean isValid(T value)
         throws IllegalArgumentException

Determines if the non-null value is valid according to the rule this validator enforces.

Implementations should check for null and throw an IllegalArgumentException, since some types of validation operations may fail to detect a null and simply return false. Loaders (which call Validators) is a probable user extension point, so consistent handling and rejection of null values is important for custom Loaders to detect logic issues.

Parameters:

value - A non-null value of type 'T'.

Returns:

boolean to indicate if the value is valid for this rule.

Throws:

IllegalArgumentException - If the value is null.

getInvalidMessage

String getInvalidMessage(T value)

A user message explaining why the value is not valid if it fails this validation rule.

The message should only refer to the value and rule criteria, and assume it is presented in a context that has already indicated an error and the Property. No leading or trailing punctuation should not be included.

Example: The value '999999999' is larger than the max value of 9999

Parameters:

value - The value which failed validation. Not null.

Returns:

A message explaining how the value violates the validation rule.

getInvalidSpecificationMessage

String getInvalidSpecificationMessage()

If the specification itself is invalid (such as a bad regex string), this will build a message describing the problem to the user.

This method may return a message regardless of if the validation is invalid or not - use isSpecificationValid() to determine if the Validator is configured correctly or not.

Returns:

A message describing an assumed problem with the validation specification.

isSpecificationValid

boolean isSpecificationValid()

Returns true if the validation criteria itself is valid.

For things like regex expressions, this would check to see if the regex expression is a valid expression.

Returns:

getTheValueMustDescription

String getTheValueMustDescription()

Get a description of the validation rule.

Assume that the text returned is prefixed with 'The value must...'

As an example for a regex rule with the pattern 'ABC.*', the return could be: "match the regex pattern 'ABC.*'"

Returns: