Package ch.frostnova.util.check

The Frostnova Check Framework offers a Check class for parameter/value validation using a rich and expandable set of utility functions.

Checks can be performed on:

• optional values (value can be null, checks only executed when it's not null)
• required values (value checked to not to be null first, remaining checks only executed when it's not null)

Failing checks result in an IllegalArgumentException, with a meaningful message which check has failed, including the parameter name.
Example:

java.lang.IllegalArgumentException: 'customer id' must have at least 6 characters

Example usage:

• Check that a value (here: parameter 'url' named 'connection url') is present (not null):
  Check.required(url, "connection url");
• Check that the name is not null, not blank and has no more than 20 characters:
  Check.required(name, "name", CheckString.notBlank(), CheckString.max(20));
• Check that an optional value is a finite number (not NaN or +/-Infinite) and > 0:
  Check.optional(val, "value", CheckNumber.finite(), CheckNumber.greaterThan(0));
• Check that a collection is not empty, and does not contain null-Elements:
  Check.required(items, "items", CheckCollection.notEmpty(), CheckCollection.noNullElements());
• Check that a String token has an expected format (alphanumeric-uppercase and exactly 32 characters):
  Check.required(token, "token", CheckString.format("[A-Z0-9]{32}", "alphanumeric uppercase"));

Custom checks can be created with any implementation of the Verify functional interface. This interface also provides static methods to create implementations based on Predicate and predefined or dynamic failure messages.

Examples for custom validation:

• Verify that a (zoned) date must be in the future
  

     Verify<ZonedDateTime> futureDate = d -> {
     if (!d.isAfter(ZonedDateTime.now())) {
       throw new IllegalArgumentException("must be in the future");
     }
   };
   Check.required(date, "execution date", futureDate);

  or

     Check.required(date, "execution date",
       Verify.that(d -> !d.isAfter(ZonedDateTime.now()), "must be in the future"));

Since:

27.05.2018.

Interface Summary

Interface	Description
Verify<T>	Verifier interface, for check to be performed with Check.

Class Summary

Class	Description
Check	Check class for input validation.
CheckCollection	Utility methods to perform checks on Collection values.
CheckNumber	Utility methods to perform checks on Number values.
CheckString	Utility methods to perform checks on String values.