org.checkerframework.framework.qual

Annotation Type Unused

@Documented
 @Retention(value=RUNTIME)
 @Target(value=FIELD)
public @interface Unused

Declares that the field may not be accessed if the receiver is of the specified qualifier type (or any supertype).

This property is verified by the checker that type-checks the when element value qualifier.

Example Consider a class, Table, with a locking field, lock. The lock is used when a Table instance is shared across threads. When running in a local thread, the lock field ought not to be used.

You can declare this behavior in the following way:

 class Table {
   private @Unused(when=LocalToThread.class) final Lock lock;
   ...
 }
 

The checker for @LocalToThread would issue an error for the following code:

  @LocalToThread Table table = ...;
   ... table.lock ...;
 

See the Checker Framework Manual:

Unused fields

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
Class<? extends Annotation>	when The field that is annotated with @Unused may not be accessed via a receiver that is annotated with the "when" annotation.

Element Detail

when

public abstract Class<? extends Annotation> when

The field that is annotated with @Unused may not be accessed via a receiver that is annotated with the "when" annotation.