| JavaTM 2 Platform Std. Ed. v1.6.0
java.lang
Class Package
java.lang.Object
 java.lang.Package
- All Implemented Interfaces:
- AnnotatedElement
public class Package - extends Object
- implements AnnotatedElement
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 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 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 RefinedVersionopt
- 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 identifiers.
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.
- See Also:
ClassLoader.definePackage(java.lang.String, java.lang.String, java.lang.String, java.lang.String, java.lang.String, java.lang.String, java.lang.String, java.net.URL)
getName
public String getName()
- Return the name of this package.
- Returns:
- The fully-qualified name of this package as defined in the
Java Language Specification, Third Edition
§6.5.3, for example, java.lang
getSpecificationTitle
public String getSpecificationTitle()
- Return the title of the specification that this package implements.
- Returns:
- the specification title, null is returned if it is not known.
getSpecificationVersion
public String getSpecificationVersion()
- Returns the version number of the specification
that this package implements.
This version string must be a sequence of positive decimal
integers separated by "."'s and may have leading zeros.
When version strings are compared the most significant
numbers are compared.
- Returns:
- the specification version, null is returned if it is not known.
getSpecificationVendor
public String getSpecificationVendor()
- Return the name of the organization, vendor,
or company that owns and maintains the specification
of the classes that implement this package.
- Returns:
- the specification vendor, null is returned if it is not known.
getImplementationTitle
public String getImplementationTitle()
- Return the title of this package.
- Returns:
- the title of the implementation, null is returned if it is not known.
getImplementationVersion
public String getImplementationVersion()
- Return the version of this implementation. It consists of any string
assigned by the vendor of this implementation and does
not have any particular syntax specified or expected by the Java
runtime. It may be compared for equality with other
package version strings used for this implementation
by this vendor for this package.
- Returns:
- the version of the implementation, null is returned if it is not known.
getImplementationVendor
public String getImplementationVendor()
- Returns the name of the organization,
vendor or company that provided this implementation.
- Returns:
- the vendor that implemented this package..
isSealed
public boolean isSealed()
- Returns true if this package is sealed.
- Returns:
- true if the package is sealed, false otherwise
isSealed
public boolean isSealed(URL url)
- Returns true if this package is sealed with respect to the specified
code source url.
- Parameters:
url - the code source url
- Returns:
- true if this package is sealed with respect to url
isCompatibleWith
public boolean isCompatibleWith(String desired)
throws NumberFormatException
- Compare this package's specification version with a
desired version. It returns true if
this packages specification version number is greater than or equal
to the desired version number.
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.
- Parameters:
desired - the version string of the desired version.
- Returns:
- true if this package's version number is greater
than or equal to the desired version number
- Throws:
NumberFormatException - if the desired or current version
is not of the correct dotted form.
getPackage
public static Package getPackage(String name)
- Find a package by name in the callers
ClassLoader instance.
The callers ClassLoader instance is used to find the package
instance corresponding to the named class. If the callers
ClassLoader instance is null then the set of packages loaded
by the system ClassLoader instance is searched to find the
named package.
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.
- Parameters:
name - a package name, for example, java.lang.
- Returns:
- the package of the requested name. It may be null if no package
information is available from the archive or codebase.
getPackages
public static Package[] getPackages()
- Get all the packages currently known for the caller's
ClassLoader
instance. Those packages correspond to classes loaded via or accessible by
name to that ClassLoader instance. If the caller's
ClassLoader instance is the bootstrap ClassLoader
instance, which may be represented by null in some implementations,
only packages corresponding to classes loaded by the bootstrap
ClassLoader instance will be returned.
- Returns:
- a new array of packages known to the callers
ClassLoader
instance. An zero length array is returned if none are known.
hashCode
public int hashCode()
- Return the hash code computed from the package name.
- Overrides:
hashCode in class Object
- Returns:
- the hash code computed from the package name.
- See Also:
Object.equals(java.lang.Object),
Hashtable
toString
public String toString()
- Returns the string representation of this Package.
Its value is the string "package " and the package name.
If the package title is defined it is appended.
If the package version is defined it is appended.
- Overrides:
toString in class Object
- Returns:
- the string representation of the package.
getAnnotation
public <A extends Annotation> A getAnnotation(Class<A> annotationClass)
- Description copied from interface:
AnnotatedElement
- Returns this element's annotation for the specified type if
such an annotation is present, else null.
- Specified by:
getAnnotation in interface AnnotatedElement
- Parameters:
annotationClass - the Class object corresponding to the
annotation type
- Returns:
- this element's annotation for the specified annotation type if
present on this element, else null
- Throws:
NullPointerException - if the given annotation class is null- Since:
- 1.5
isAnnotationPresent
public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass)
- Description copied from interface:
AnnotatedElement
- Returns true if an annotation for the specified type
is present on this element, else false. This method
is designed primarily for convenient access to marker annotations.
- Specified by:
isAnnotationPresent in interface AnnotatedElement
- Parameters:
annotationClass - the Class object corresponding to the
annotation type
- Returns:
- true if an annotation for the specified annotation
type is present on this element, else false
- Throws:
NullPointerException - if the given annotation class is null- Since:
- 1.5
getAnnotations
public Annotation[] getAnnotations()
- Description copied from interface:
AnnotatedElement
- Returns all annotations present on this element. (Returns an array
of length zero if this element has no annotations.) The caller of
this method is free to modify the returned array; it will have no
effect on the arrays returned to other callers.
- Specified by:
getAnnotations in interface AnnotatedElement
- Returns:
- all annotations present on this element
- Since:
- 1.5
getDeclaredAnnotations
public Annotation[] getDeclaredAnnotations()
- Description copied from interface:
AnnotatedElement
- Returns all annotations that are directly present on this
element. Unlike the other methods in this interface, this method
ignores inherited annotations. (Returns an array of length zero if
no annotations are directly present on this element.) The caller of
this method is free to modify the returned array; it will have no
effect on the arrays returned to other callers.
- Specified by:
getDeclaredAnnotations in interface AnnotatedElement
- Returns:
- All annotations directly present on this element
- Since:
- 1.5
Copyright 2003 Sun Microsystems, Inc. All rights reserved
|
