Package Reflection
The java.lang.Package class provides access to information about a package.
Package objects contain version information about a Java package.
Get package for a name
static Package getPackage(String name)- Find a package by name in the callers ClassLoader instance.
Get all packages
static Package[] getPackages()- Get all the packages currently known for the caller's ClassLoader instance.
Get the annotations
<A extends Annotation>A getAnnotation(Class<A> annotationClass)- Returns this element's annotation for the specified type if such an annotation is present, else null.
Annotation[] getAnnotations()- Returns all annotations present on this element.
Annotation[] getDeclaredAnnotations()- Returns all annotations that are directly present on this element.
Get implementation title, vendor and version
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.
Get the package name
String getName()- Return the name of this package.
Get the specification title, vendor and version
String getSpecificationTitle()- Return the title of the specification.
String getSpecificationVendor()- Return the name of the organization, vendor.
String getSpecificationVersion()- Returns the version number.
Is Annotation present
boolean isAnnotationPresent(Class<? extends Annotation> annotationClass)- Returns true if an annotation for the specified type is present on this element, else false.
Is this Package compatible with passed in package
boolean isCompatibleWith(String desired)- Compare this package's specification version with a desired version.
Is this Package sealed
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.
Get the string representation of the Package
String toString()- Returns the string representation of this Package.
Revised from Open JDK source code
public class Main {
public static void main(String[] args) {
Package pkg = Package.getPackage("java.lang");
System.out.println("Name: " + pkg.getName());
System.out.println("Implementation title: " + pkg.getImplementationTitle());
System.out.println("Implementation vendor: " + pkg.getImplementationVendor());
System.out.println("Implementation version: " + pkg.getImplementationVersion());
System.out.println("Specification title: " + pkg.getSpecificationTitle());
System.out.println("Specification vendor: " + pkg.getSpecificationVendor());
System.out.println("Specification version: " + pkg.getSpecificationVersion());
System.out.println("Sealed: " + pkg.isSealed());
System.out.println("Compatible: " + pkg.isCompatibleWith("1.3"));
}
}