AnnotatedElement
public class Package extends Object implements AnnotatedElement
Annotations for the run-time package are read from package-info.class
at the same code source as classes in the run-time package.
The set of classes that make up the run-time package may implement a particular specification. The specification title, version, and vendor (indicating the owner/maintainer of the specification) can be provided when the Package
is defined. An application can ask if the Package
is compatible with a particular specification version by using the Package.isCompatibleWith(String)
method. In addition, information about the actual classes that make up the run-time package can be provided when the Package
is defined. This information consists of an implementation title, version, and vendor (indicating the supplier of the classes).
A Package
may be explicitly defined with the ClassLoader.definePackage(String, String, String, String, String, String, String, URL)
method. The caller supplies the specification and implementation titles, versions, and vendors. The caller also indicates whether the package is sealed. If a Package
is not explicitly defined for a run-time package when a class in that run-time package is defined, then a Package
is automatically defined by the class's defining class loader, as follows.
A Package
automatically defined for classes in a named module has the following properties:
package-info.class
as specified above. A Package
automatically defined for classes in an unnamed module has the following properties:
""
(for classes in an unnamed package) or derived from the binary names of the classes (for classes in a named package).package-info.class
as specified above. A Package
can be obtained with the Package.getPackage(String)
and ClassLoader.getDefinedPackage(String)
methods. Every Package
defined by a class loader can be obtained with the Package.getPackages()
and ClassLoader.getDefinedPackages()
methods.
Package
objects for packages in named modules. Instead those packages are automatically defined and have no specification and implementation versioning information.Modifier and Type | Method | Description |
---|---|---|
<A extends Annotation> |
getAnnotation |
Returns this element's annotation for the specified type if such an annotation is present, else null. |
Annotation[] |
getAnnotations() |
Returns annotations that are present on this element. |
<A extends Annotation> |
getAnnotationsByType |
Returns annotations that are associated with this element. |
<A extends Annotation> |
getDeclaredAnnotation |
Returns this element's annotation for the specified type if such an annotation is directly present, else null. |
Annotation[] |
getDeclaredAnnotations() |
Returns annotations that are directly present on this element. |
<A extends Annotation> |
getDeclaredAnnotationsByType |
Returns this element's annotation(s) for the specified type if such annotations are either directly present or indirectly present. |
String |
getImplementationTitle() |
Return the title of this package. |
String |
getImplementationVendor() |
Returns the vendor that implemented this package, null is returned if it is not known. |
String |
getImplementationVersion() |
Return the version of this implementation. |
String |
getName() |
Return the name of this package. |
static Package |
getPackage |
Deprecated. |
static Package[] |
getPackages() |
Returns all of the Package s defined by the caller's class loader and its ancestors. |
String |
getSpecificationTitle() |
Return the title of the specification that this package implements. |
String |
getSpecificationVendor() |
Return the name of the organization, vendor, or company that owns and maintains the specification of the classes that implement this package. |
String |
getSpecificationVersion() |
Returns the version number of the specification that this package implements. |
int |
hashCode() |
Return the hash code computed from the package name. |
boolean |
isAnnotationPresent |
Returns true if an annotation for the specified type is present on this element, else false. |
boolean |
isCompatibleWith |
Compare this package's specification version with a desired version. |
boolean |
isSealed() |
Returns true if this package is sealed. |
boolean |
isSealed |
Returns true if this package is sealed with respect to the specified code source url . |
String |
toString() |
Returns the string representation of this Package. |
public String getName()
java.lang
public String getSpecificationTitle()
null
is returned if it is not known.public String getSpecificationVersion()
Specification version numbers use a syntax that consists of non-negative decimal integers separated by periods ".", for example "2.0" or "1.2.3.4.5.6.7". This allows an extensible number to be used to represent major, minor, micro, etc. versions. The version specification is described by the following formal grammar:
- SpecificationVersion:
- Digits RefinedVersionopt
- RefinedVersion:
.
Digits.
Digits RefinedVersion- Digits:
- Digit
- Digits
- Digit:
- any character for which
Character.isDigit(char)
returnstrue
, e.g. 0, 1, 2, ...
null
is returned if it is not known.public String getSpecificationVendor()
null
is returned if it is not known.public String getImplementationTitle()
null
is returned if it is not known.public String getImplementationVersion()
null
is returned if it is not known.public String getImplementationVendor()
null
is returned if it is not known.null
is returned if it is not known.public boolean isSealed()
Package
class specification for details how a Package
is defined as sealed package.public boolean isSealed(URL url)
url
.Package
class specification for details how a Package
is defined as sealed package.url
- the code source URLurl
public boolean isCompatibleWith(String desired) throws NumberFormatException
Version numbers are compared by sequentially comparing corresponding components of the desired and specification strings. Each component is converted as a decimal integer and the values compared. If the specification value is greater than the desired value true is returned. If the value is less false is returned. If the values are equal the period is skipped and the next pair of components is compared.
desired
- the version string of the desired version.NumberFormatException
- if the current version is not known or the desired or current version is not of the correct dotted form.@Deprecated(since="9") public static Package getPackage(String name)
getPackage
to return a Package
from a parent loader, then the properties exposed by the Package
may not be as expected in the rest of the program. For example, the Package
will only expose annotations from the package-info.class
file defined by the parent loader, even if annotations exist in a package-info.class
file defined by a child loader. A more robust approach is to use the ClassLoader.getDefinedPackage(java.lang.String)
method which returns a Package
for the specified class loader. If the caller's class loader defines a Package
of the given name, the Package
is returned. Otherwise, the ancestors of the caller's class loader are searched recursively (parent by parent) for a Package
of the given name.
Calling this method is equivalent to calling ClassLoader.getPackage(java.lang.String)
on a ClassLoader
instance which is the caller's class loader.
name
- A package name, such as "java.lang
".Package
of the given name defined by the caller's class loader or its ancestors, or null
if not found.NullPointerException
- if name
is null
.public static Package[] getPackages()
Package
s defined by the caller's class loader and its ancestors. The returned array may contain more than one Package
object of the same package name, each defined by a different class loader in the class loader hierarchy. Calling this method is equivalent to calling ClassLoader.getPackages()
on a ClassLoader
instance which is the caller's class loader.
Package
objects defined by this class loader and its ancestorspublic int hashCode()
public String toString()
public <A extends Annotation> A getAnnotation(Class<A> annotationClass)
Note that any annotation returned by this method is a declaration annotation.
getAnnotation
in interface AnnotatedElement
A
- the type of the annotation to query for and return if presentannotationClass
- the Class object corresponding to the annotation typeNullPointerException
- if the given annotation class is nullpublic boolean isAnnotationPresent(Class<? extends Annotation> annotationClass)
The truth value returned by this method is equivalent to: getAnnotation(annotationClass) != null
isAnnotationPresent
in interface AnnotatedElement
annotationClass
- the Class object corresponding to the annotation typeNullPointerException
- if the given annotation class is nullpublic <A extends Annotation> A[] getAnnotationsByType(Class<A> annotationClass)
AnnotatedElement.getAnnotation(Class)
is that this method detects if its argument is a repeatable annotation type (JLS 9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers. Note that any annotations returned by this method are declaration annotations.
getAnnotationsByType
in interface AnnotatedElement
A
- the type of the annotation to query for and return if presentannotationClass
- the Class object corresponding to the annotation typeNullPointerException
- if the given annotation class is nullpublic Annotation[] getAnnotations()
Note that any annotations returned by this method are declaration annotations.
getAnnotations
in interface AnnotatedElement
public <A extends Annotation> A getDeclaredAnnotation(Class<A> annotationClass)
Note that any annotation returned by this method is a declaration annotation.
getDeclaredAnnotation
in interface AnnotatedElement
A
- the type of the annotation to query for and return if directly presentannotationClass
- the Class object corresponding to the annotation typeNullPointerException
- if the given annotation class is nullpublic <A extends Annotation> A[] getDeclaredAnnotationsByType(Class<A> annotationClass)
AnnotatedElement
AnnotatedElement.getDeclaredAnnotation(Class)
is that this method detects if its argument is a repeatable annotation type (JLS 9.6), and if so, attempts to find one or more annotations of that type by "looking through" a container annotation if one is present. The caller of this method is free to modify the returned array; it will have no effect on the arrays returned to other callers.getDeclaredAnnotationsByType
in interface AnnotatedElement
A
- the type of the annotation to query for and return if directly or indirectly presentannotationClass
- the Class object corresponding to the annotation typeNullPointerException
- if the given annotation class is nullpublic Annotation[] getDeclaredAnnotations()
Note that any annotations returned by this method are declaration annotations.
getDeclaredAnnotations
in interface AnnotatedElement
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Package.html
getPackage
to return aPackage
from a parent loader, then the properties exposed by thePackage
may not be as expected in the rest of the program.