Package org.jetbrains.annotations
Annotation Type Nullable
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@Documented @Retention(CLASS) @Target({METHOD,FIELD,PARAMETER,LOCAL_VARIABLE,TYPE_USE}) public @interface Nullable
An element annotated withNullable
claimsnull
value is perfectly valid to return (for methods), pass to (parameters) or hold in (local variables and fields). Apart from documentation purposes this annotation is intended to be used by static analysis tools to validate against probable runtime errors or element contract violations.
By convention, this annotation applied only when the value should always be checked againstnull
because the developer could do nothing to prevent null from happening. Otherwise, too eagerNullable
usage could lead to too many false positives from static analysis tools.
For example,Map.get(Object key)
should not be annotatedNullable
because someone may have put not-null value in the map by this key and is expecting to find this value there ever since.
On the other hand, theReference.get()
should be annotatedNullable
because it returnsnull
if object got collected which can happen at any time completely unexpectedly.
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Element Detail
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value
String value
- Default:
- ""
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