AnnotatedElementpublic 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 Packages 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()
Packages 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)
AnnotatedElementAnnotatedElement.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
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/lang/Package.html
getPackageto return aPackagefrom a parent loader, then the properties exposed by thePackagemay not be as expected in the rest of the program.