Package class in Java

java.lang.Package

Represents metadata about a run-time package associated with a class loader. Metadata includes annotations, versioning, and sealing.

Annotations for the run-time package are read from the package info. class at the same code source as classes in the run-time package.

A Package automatically defined for classes in a named module has the following properties:

1. The name of the package is derived from the binary names of the classes. Since classes in a named module must be in a named package, the derived name is never empty.

2. The package is sealed with the module location as the code source, if known.

3. The specification and implementation titles, versions, and vendors are unspecified.

4. Any annotations on the package are read from package-info. classes specified above.

A Package automatically defined for classes in an unnamed module has the following properties:

1. The name of the package is either "" (for classes in an unnamed package)or derived from the binary names of the classes(for classes in a named package).

2. The package is not sealed.

3. The specification and implementation titles, versions, and vendors are unspecified.

4. Any annotations on the package are read from package-info. classes specified above.

Some methods of Package Class

getAnnotation(Class): This method returns this element's annotation for the specified type if such an annotation is present, else null.

getAnnotations(): This method returns annotations that are present on this element.

getAnnotationsByType(Class): This method returns annotations that are associated with this element.

getDeclaredAnnotation(Class): This method returns this element's annotation for the specified type if such an annotation is directly present, else null. This method ignores inherited annotations.

getDeclaredAnnotations(): This method returns annotations that are directly present on this element. This method ignores inherited annotations.

getDeclaredAnnotationsByType(Class): This method returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present.

getImplementationTitle(): This method returns the title of this package.

getImplementationVendor(): This method returns the vendor that implemented this package, null is returned if it is not known.

getImplementationVersion(): This method returns the version of this implementation.

getName(): This method returns the name of this package.

getPackages(): This method returns all of the Packages defined by the caller's class loader and its ancestors.

getSpecificationTitle(): This method returns the title of the specification that this package implements.

getSpecificationVendor(): This method returns the name of the organization, vendor, or company that owns and maintains the specification of the classes that implement this package.

getSpecificationVersion(): This method returns the version number of the specification that this package implements.

hashCode(): This method returns the hash code computed from the package name.

isAnnotationPresent(Class): This method returns true if an annotation for the specified type is present on this element, else false.

isCompatibleWith(String): This method compares this package's specification version with the desired version.

isSealed(): This method returns true if this package is sealed.

isSealed(URL): This method returns true if this package is sealed with respect to the specified code source URL.

toString(): This method returns the string representation of this Package.