Interfaces used to model elements of the Java programming language. The term "element" in this package is used to refer to program elements, the declared entities that make up a program. Elements include classes, interfaces, methods, constructors, and fields. The interfaces in this package do not model the structure of a program inside a method body; for example there is no representation of a for loop or try-finally block. However, the interfaces can model some structures only appearing inside method bodies, such as local variables and anonymous classes.

When used in the context of annotation processing, an accurate model of the element being represented must be returned. As this is a language model, the source code provides the fiducial (reference) representation of the construct in question rather than a representation in an executable output like a class file. Executable output may serve as the basis for creating a modeling element. However, the process of translating source code to executable output may not permit recovering some aspects of the source code representation. For example, annotations with source retention cannot be recovered from class files and class files might not be able to provide source position information. The modifiers on an element may differ in some cases including

• strictfp on a class or interface
• final on a parameter
• protected, private, and static on classes and interfaces

Additionally, synthetic constructs in a class file, such as accessor methods used in implementing nested classes and bridge methods used in implementing covariant returns, are translation artifacts outside of this model.

During annotation processing, operating on incomplete or erroneous programs is necessary; however, there are fewer guarantees about the nature of the resulting model. If the source code is not syntactically well-formed or has some other irrecoverable error that could not be removed by the generation of new types, a model may or may not be provided as a quality of implementation issue. If a program is syntactically valid but erroneous in some other fashion, any returned model must have no less information than if all the method bodies in the program were replaced by "throw new RuntimeException();". If a program refers to a missing type XYZ, the returned model must contain no less information than if the declaration of type XYZ were assumed to be "class XYZ {}", "interface XYZ {}", "enum XYZ {}", or "@interface XYZ {}". If a program refers to a missing type XYZ<K1, ... ,Kn>, the returned model must contain no less information than if the declaration of XYZ were assumed to be "class XYZ<T1, ... ,Tn> {}" or "interface XYZ<T1, ... ,Tn> {}"

Unless otherwise specified in a particular implementation, the collections returned by methods in this package should be expected to be unmodifiable by the caller and unsafe for concurrent access.

Unless otherwise specified, methods in this package will throw a NullPointerException if given a null argument.