Package JDK 1.6)

Description

public class Package

Package objects contain version information about the implementation and specification of a Java 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 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)

Methods

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public A getAnnotation (Class< A> annotationClass)

public Annotation getAnnotations () [Specified in AnnotatedElement]

public Annotation getDeclaredAnnotations () [Specified in AnnotatedElement]

public String getImplementationTitle ()

Return the title of this package.

public String getImplementationVendor ()

Returns the name of the organization, vendor or company that provided this implementation.

public String getImplementationVersion ()

Return the version of this implementation.

public String getName ()

Return the name of this package.

pack-privatestatic Package getPackage (Class c)

Get the package for the specified class.

Get the package for the specified class. The class's class loader is used to find the package instance corresponding to the specified class. If the class loader is the bootstrap class loader, which may be represented by null in some implementations, then the set of packages loaded by the bootstrap class loader is searched to find the 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.
Returns: the package of the class. It may be null if no package information is available from the archive or codebase.
Parameters:
- class - the class to get the package of.

publicstatic Package getPackage (String name)

Find a package by name in the callers ClassLoader instance.

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.
Returns: the package of the requested name. It may be null if no package information is available from the archive or codebase.
Parameters:
- name - a package name, for example, java.lang.

publicstatic Package getPackages ()

Get all the packages currently known for the caller's ClassLoader instance.

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.

public String getSpecificationTitle ()

Return the title of the specification that this package implements.

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.

public String getSpecificationVersion ()

Returns the version number of the specification that this package implements.

pack-privatestatic Package getSystemPackage (String name)

pack-privatestatic Package getSystemPackages ()

public int hashCode ()

Return the hash code computed from the package name.

public boolean isAnnotationPresent (Class<Annotation> annotationClass) [Specified in AnnotatedElement]

public boolean isCompatibleWith (String desired) throws NumberFormatException

Compare this package's specification version with a desired version.

public boolean isSealed ()

Returns true if this package is sealed.

public boolean isSealed (URL url)

Returns true if this package is sealed with respect to the specified code source url.

public String toString ()

Returns the string representation of this Package.