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JavaTM 2 Platform Standard Edition |
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SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
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 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 "Dewey Decimal" 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 number must begin with a number.
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 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.
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)
Method Summary | |
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. |
static Package[] |
getPackages()
Get all the packages currently known for the caller's class loader. |
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 hashcode computed from the package name. |
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 |
clone,
equals,
finalize,
getClass,
notify,
notifyAll,
wait,
wait,
wait |
Method Detail |
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)
url
- the code source urlpublic 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.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.
packageName
- a package name, for example, java.lang.public static Package[] getPackages()
null
in some implementations, only packages corresponding
to classes loaded by the bootstrap class loader will be returned.public int hashCode()
public String toString()
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JavaTM 2 Platform Standard Edition |
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