Package java.lang

Class Package

java.lang.Object
java.lang.Package
All Implemented Interfaces:
AnnotatedElement
public class Package
extends Object
implements AnnotatedElement
Contains information about a Java package. This includes implementation and specification versions. Typically this information is retrieved from the manifest.

Packages are managed by class loaders. All classes loaded by the same loader from the same package share a Package instance.

See Also:
ClassLoader

  • Method Details

    • getAnnotation

      public <A extends Annotation> A getAnnotation​(Class<A> annotationType)
      Returns the annotation associated with the specified annotation type and this package, if present.
      Specified by:
      getAnnotation in interface AnnotatedElement
      Parameters:
      annotationType - the annotation type to look for.
      Returns:
      an instance of Annotation or null.
      See Also:
      AnnotatedElement.getAnnotation(java.lang.Class)

    • getAnnotations

      public Annotation[] getAnnotations()
      Returns an array of this package's annotations.
      Specified by:
      getAnnotations in interface AnnotatedElement
      Returns:
      an array of all annotations for this element

    • getDeclaredAnnotations

      public Annotation[] getDeclaredAnnotations()
      Returns an array of this package's declared annotations. Package annotations aren't inherited, so this is equivalent to getAnnotations().
      Specified by:
      getDeclaredAnnotations in interface AnnotatedElement
      Returns:
      an array of annotations declared for this element

    • isAnnotationPresent

      public boolean isAnnotationPresent​(Class<? extends Annotation> annotationType)
      Indicates whether the specified annotation is present.
      Specified by:
      isAnnotationPresent in interface AnnotatedElement
      Parameters:
      annotationType - the annotation type to look for.
      Returns:
      true if the annotation is present; false otherwise.
      See Also:
      AnnotatedElement.isAnnotationPresent(java.lang.Class)

    • getImplementationTitle

      public String getImplementationTitle()
      Returns the title of the implementation of this package, or null if this is unknown. The format of this string is unspecified.
      Returns:
      the implementation title, may be null.

    • getImplementationVendor

      public String getImplementationVendor()
      Returns the name of the vendor or organization that provides this implementation of the package, or null if this is unknown. The format of this string is unspecified.
      Returns:
      the implementation vendor name, may be null.

    • getImplementationVersion

      public String getImplementationVersion()
      Returns the version of the implementation of this package, or null if this is unknown. The format of this string is unspecified.
      Returns:
      the implementation version, may be null.

    • getName

      public String getName()
      Returns the name of this package in the standard dot notation; for example: "java.lang".
      Returns:
      the name of this package.

    • getPackage

      public static Package getPackage​(String packageName)
      Attempts to locate the requested package in the caller's class loader. If no package information can be located, null is returned.
      Parameters:
      packageName - the name of the package to find.
      Returns:
      the requested package, or null.
      See Also:
      ClassLoader.getPackage(java.lang.String)

    • getPackages

      public static Package[] getPackages()
      Returns all the packages known to the caller's class loader.
      Returns:
      all the packages known to the caller's class loader.
      See Also:
      ClassLoader.getPackages()

    • getSpecificationTitle

      public String getSpecificationTitle()
      Returns the title of the specification this package implements, or null if this is unknown.
      Returns:
      the specification title, may be null.

    • getSpecificationVendor

      public String getSpecificationVendor()
      Returns the name of the vendor or organization that owns and maintains the specification this package implements, or null if this is unknown.
      Returns:
      the specification vendor name, may be null.

    • getSpecificationVersion

      public String getSpecificationVersion()
      Returns the version of the specification this package implements, or null if this is unknown. The version string is a sequence of non-negative integers separated by dots; for example: "1.2.3".
      Returns:
      the specification version string, may be null.

    • hashCode

      public int hashCode()
      Description copied from class: Object
      Returns an integer hash code for this object. By contract, any two objects for which Object.equals(java.lang.Object) returns true must return the same hash code value. This means that subclasses of Object usually override both methods or neither method.

      Note that hash values must not change over time unless information used in equals comparisons also changes.

      See Writing a correct hashCode method if you intend implementing your own hashCode method.

      Overrides:
      hashCode in class Object
      Returns:
      this object's hash code.
      See Also:
      Object.equals(java.lang.Object)

    • isCompatibleWith

      public boolean isCompatibleWith​(String version) throws NumberFormatException
      Indicates whether this package's specification version is compatible with the specified version string. Version strings are compared by comparing each dot separated part of the version as an integer.
      Parameters:
      version - the version string to compare against.
      Returns:
      true if the package versions are compatible; false otherwise.
      Throws:
      NumberFormatException - if this package's version string or the one provided are not in the correct format.

    • isSealed

      public boolean isSealed()
      Indicates whether this package is sealed.
      Returns:
      true if this package is sealed; false otherwise.

    • isSealed

      public boolean isSealed​(URL url)
      Indicates whether this package is sealed with respect to the specified URL.
      Parameters:
      url - the URL to check.
      Returns:
      true if this package is sealed with url; false otherwise

    • toString

      public String toString()
      Description copied from class: Object
      Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression: 
         getClass().getName() + '@' + Integer.toHexString(hashCode())

      See Writing a useful toString method if you intend implementing your own toString method.

      Overrides:
      toString in class Object
      Returns:
      a printable representation of this object.