Java Metadata Facility

Journal Article · Thu Mar 06 04:00:00 EST 2008 · Encyclopedia of Database Systems, N/A, N/A, November 1, 2009, pp. 1580

OSTI ID:973644

Buttler, D J

The Java Metadata Facility is introduced by Java Specification Request (JSR) 175 [1], and incorporated into the Java language specification [2] in version 1.5 of the language. The specification allows annotations on Java program elements: classes, interfaces, methods, and fields. Annotations give programmers a uniform way to add metadata to program elements that can be used by code checkers, code generators, or other compile-time or runtime components. Annotations are defined by annotation types. These are defined the same way as interfaces, but with the symbol {at} preceding the interface keyword. There are additional restrictions on defining annotation types: (1) They cannot be generic; (2) They cannot extend other annotation types or interfaces; (3) Methods cannot have any parameters; (4) Methods cannot have type parameters; (5) Methods cannot throw exceptions; and (6) The return type of methods of an annotation type must be a primitive, a String, a Class, an annotation type, or an array, where the type of the array is restricted to one of the four allowed types. See [2] for additional restrictions and syntax. The methods of an annotation type define the elements that may be used to parameterize the annotation in code. Annotation types may have default values for any of its elements. For example, an annotation that specifies a defect report could initialize an element defining the defect outcome submitted. Annotations may also have zero elements. This could be used to indicate serializability for a class (as opposed to the current Serializability interface).

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 973644
• Report Number(s): LLNL-JRNL-402071
• Journal Information: Encyclopedia of Database Systems, N/A, N/A, November 1, 2009, pp. 1580, Journal Name: Encyclopedia of Database Systems, N/A, N/A, November 1, 2009, pp. 1580
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS
DEFECTS
JAVA
SPECIFICATIONS