@Target(value=ANNOTATION_TYPE)
@Retention(value=RUNTIME)
public @interface MonotonicQualifier
T to another qualifier S. The annotation S is
called the target of the monotonic qualifier, and has to be indicated by value().
This meta-annotation can be used on the declaration of the monotonic qualifier used for the
type-system at hand, and is often called MonoT if the target is T. The subtyping
hierarchy has to be defined as follows:
T <: MonoT <: S
<: indicates the subtyping relation.
An expression of a monotonic type can only be assigned expressions of the target type T. This means that an expression of the monotonic type MonoT cannot be assigned to a
variable of the same type.
Reading an expression of a monotonic type MonoT might always yield an expression of
type S. However, once it has been observed that a variable has the target type T,
the monotonic property ensures that it will stay of type T for the rest of the program
execution. This is even true if arbitrary other code is executed.
Note that variables of a monotonic type can be re-assigned arbitrarily often, but only with expressions of the target type.
| Modifier and Type | Required Element and Description |
|---|---|
java.lang.Class<? extends java.lang.annotation.Annotation> |
value |