@Ensure annotation

Action

(Available since v1.1)
Design-By-Contract annotation that declares the postconditions of a method. The postconditions are expressed using any Java-compliant (JSR 223) scripting engine, and must be true after the body of the method is executed. If the postconditions fail, a ConstraintViolationException will be thrown.

The script can be specified either in the same location or can be placed in an external location. The script receives the following variables :

__data - The data being validated
__paramNN - The nth parameter of the method (__param0 being the first parameter)
__result - The result of the method.
__this , __instance - The instance to which the property being validated belongs
__name - The name of the property being validated
__env - The validation environment
__cfg - The configuration of this annotation

The script must return true if the data is valid, or false otherwise

Note that in order to execute design by contract annotations automatically, you must enable AspectJ in your project, as described here.

Javadoc Ref : @Ensure

Input Types ¹	Object
Output Types	Same as input

¹Automatic conversion will take place if the provided input does not match any of the input classes, as described in the conversions part of the manual.

Arguments

language	Language of the script. Default is "JavaScript".
script	Script code
scriptResource	Name of an external resource containing the script code
resourceEncoding	If the script is specified externally, this attribute specifies the character encoding used in the resource. Default is iso-8859-1
exceptionPolicy	Specifies what happens if the script throws an exception. Can be one of the following values (all of them belonging to the ExceptionPolicy enumeration) ASSUME_ VALID : The value is assumed to be valid ASSUME_INVALID : The value is assumed to be invalid PROPAGATE : The exception is propagated to the user code as a HandlerException
scriptFunction	Specifies which function from the script to call. If not specified, the script will be executed using "immediate mode". Otherwise, the specified function will be invoked, and will be passed the following parameters (in order): Validation environment Property name Object instance Data value to be validated The function must return a true/false result.

Example

@Ensure("__result > 0 ")
public int sum(@MinInclusive(3) int a, @MinInclusive(3) int b) {
return a +b;
}