java.lang.Object java.lang.Package
Package objects contain version information about the implementation and specification of a Java package. This versioning information is retrieved and made available by the ClassLoader instance that loaded the class(es). Typically, it is stored in the manifest that is distributed with the classes.
The set of classes that make up the package may implement a particular specification and if so the specification title, version number, and vendor strings identify that specification. An application can ask if the package is compatible with a particular version, see the isCompatibleWith method for details.
Specification version numbers use a syntax that consists of positive 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 RefinedVersion opt
- RefinedVersion:
- . Digits
- . Digits RefinedVersion
- Digits:
- Digit
- Digits
- Digit:
- any character for which Character.isDigit(char) returns true, e.g. 0, 1, 2, ...
The implementation title, version, and vendor strings identify an implementation and are made available conveniently to enable accurate reporting of the packages involved when a problem occurs. The contents all three implementation strings are vendor specific. The implementation version strings have no specified syntax and should only be compared for equality with desired version identifers.
Within each ClassLoader instance all classes from the same java package have the same Package object. The static methods allow a package to be found by name or the set of all packages known to the current class loader to be found.
Method Summary | ||
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getAnnotation
(
Class
<A> annotationClass)
|
|
java.lang.annotation.Annotation[] |
getAnnotations
()
Returns all annotations present on this element. |
|
java.lang.annotation.Annotation[] |
getDeclaredAnnotations
()
Returns all annotations that are directly present on this element. |
|
String |
getImplementationTitle
() Return the title of this package. |
|
String |
getImplementationVendor
() Returns the name of the organization, vendor or company that provided this implementation. |
|
String |
getImplementationVersion
() Return the version of this implementation. |
|
String |
getName
() Return the name of this package. |
|
static Package |
getPackage
(
String
name) Find a package by name in the callers ClassLoader instance. |
|
static Package [] |
getPackages
() Get all the packages currently known for the caller's ClassLoader instance. |
|
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
(
Class
Returns true if an annotation for the specified type is present on this element, else false. |
|
boolean |
isCompatibleWith
(
String
desired) Compare this package's specification version with a desired version. |
|
boolean |
isSealed
() Returns true if this package is sealed. |
|
boolean |
isSealed
(
URL
url) Returns true if this package is sealed with respect to the specified code source url. |
|
String |
toString
() Returns the string representation of this Package. |
Methods inherited from class java.lang. Object |
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clone , equals , finalize , getClass , notify , notifyAll , wait , wait , wait |
Methods inherited from interface java.lang.reflect. AnnotatedElement |
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getAnnotation |
Method Detail |
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public String getName()
public String getSpecificationTitle()
public String getSpecificationVersion()
public String getSpecificationVendor()
public String getImplementationTitle()
public String getImplementationVersion()
public String getImplementationVendor()
public boolean isSealed()
public boolean isSealed(URL url)
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.
public static Package getPackage(String name)
Packages have attributes for versions and specifications only if the class loader created the package instance with the appropriate attributes. Typically, those attributes are defined in the manifests that accompany the classes.
public static Package[] getPackages()
public int hashCode()
public String toString()
public <A extends java.lang.annotation.Annotation> A getAnnotation ( Class<A> annotationClass)
public boolean isAnnotationPresent ( Class<? extends java.lang.annotation.Annotation> annotationClass)
public java.lang.annotation.Annotation[] getAnnotations ()
public java.lang.annotation.Annotation[] getDeclaredAnnotations ()