org.checkerframework.checker.initialization.qual

Annotation Type UnknownInitialization

@SubtypeOf(value={})
 @DefaultFor(value={LOCAL_VARIABLE,RESOURCE_VARIABLE})
 @Documented
 @Retention(value=RUNTIME)
 @Target(value={TYPE_USE,TYPE_PARAMETER})
public @interface UnknownInitialization

This type qualifier belongs to the freedom-before-commitment type-system for tracking initialization. This type-system is not used on its own, but in conjunction with some other type-system that wants to ensure safe initialization. For instance, NullnessChecker uses freedom-before-commitment to track initialization of NonNull fields.

This type qualifier indicates that the object might not have been fully initialized. An object is fully initialized when each of its fields contains a value that satisfies its type qualifier. What type qualifiers are considered depends on the checker; for instance, the NullnessChecker considers NonNull.

Therefore, reading a field of an object of type UnknownInitialization might yield a value that does not correspond to the declared type qualifier for that field. For instance, in the NullnessChecker, a field might be null even if it has been annotated as NonNull.

More precisely, an expression of type @UnknownInitialization(T.class) refers to an object that has all fields of T (and any super-classes) initialized (e.g., to a non-null value in the NullnessChecker). Just @UnknownInitialization is equivalent to @UnknownInitialization(Object.class).

See the Checker Framework Manual:

Initialization Checker

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
Class<?>	value The type-frame down to which the expression (of this type) has been initialized at least (inclusive).

Element Detail

value

public abstract Class<?> value

The type-frame down to which the expression (of this type) has been initialized at least (inclusive). That is, an expression of type @UnknownInitialization(T.class) has all type-frames initialized starting at Object down to (and including) T.

Default:

java.lang.Object.class