|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
public interface Constraint<E>
A constraint that an element must satisfy in order to be added to a
collection. For example, Constraints.NOT_NULL
, which prevents a
collection from including any null elements, could be implemented like this:
public void checkElement(Object element) { if (element == null) { throw new NullPointerException(); } }
In order to be effective, constraints should be deterministic; that is, they should not depend on state that can change (such as external state, random variables, and time) and should only depend on the value of the passed-in element. A non-deterministic constraint cannot reliably enforce that all the collection's elements meet the constraint, since the constraint is only enforced when elements are added.
Constraints
,
MapConstraint
Method Summary | |
---|---|
void |
checkElement(E element)
Throws a suitable RuntimeException if the specified element is
illegal. |
String |
toString()
Returns a brief human readable description of this constraint, such as "Not null" or "Positive number". |
Method Detail |
---|
void checkElement(E element)
RuntimeException
if the specified element is
illegal. Typically this is either a NullPointerException
, an
IllegalArgumentException
, or a ClassCastException
, though
an application-specific exception class may be used if appropriate.
String toString()
toString
in class Object
|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |