Extension (Apache Ant API)
Date: 2018-07-10

org.apache.tools.ant.taskdefs.optional.extension

## Class Extension

- java.lang.Object
- - org.apache.tools.ant.taskdefs.optional.extension.Extension

-     public final class Extension
      extends java.lang.Object

  Utility class that represents either an available "Optional Package" (formerly known as "Standard Extension") as described in the manifest of a JAR file, or the requirement for such an optional package.

  For more information about optional packages, see the document Optional Package Versioning in the documentation bundle for your Java2 Standard Edition package, in file `guide/extensions/versioning.html`.

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static Compatibility` | `COMPATIBLE` Enum indicating that extension is compatible with other extension.
    `static java.util.jar.Attributes.Name` | `EXTENSION_LIST` Manifest Attribute Name object for EXTENSION_LIST.
    `static java.util.jar.Attributes.Name` | `EXTENSION_NAME` Manifest Attribute Name object for EXTENSION_NAME.
    `static java.util.jar.Attributes.Name` | `IMPLEMENTATION_URL` Manifest Attribute Name object for IMPLEMENTATION_URL.
    `static java.util.jar.Attributes.Name` | `IMPLEMENTATION_VENDOR` Manifest Attribute Name object for IMPLEMENTATION_VENDOR.
    `static java.util.jar.Attributes.Name` | `IMPLEMENTATION_VENDOR_ID` Manifest Attribute Name object for IMPLEMENTATION_VENDOR_ID.
    `static java.util.jar.Attributes.Name` | `IMPLEMENTATION_VERSION` Manifest Attribute Name object for IMPLEMENTATION_VERSION.
    `static Compatibility` | `INCOMPATIBLE` Enum indicating that extension is incompatible with other extension in ways other than other enums indicate).
    `static java.util.jar.Attributes.Name` | `OPTIONAL_EXTENSION_LIST` `Name` object for `Optional-Extension-List` manifest attribute used for declaring optional dependencies on installed extensions.
    `static Compatibility` | `REQUIRE_IMPLEMENTATION_UPGRADE` Enum indicating that extension requires an upgrade of implementation to be compatible with other extension.
    `static Compatibility` | `REQUIRE_SPECIFICATION_UPGRADE` Enum indicating that extension requires an upgrade of specification to be compatible with other extension.
    `static Compatibility` | `REQUIRE_VENDOR_SWITCH` Enum indicating that extension requires a vendor switch to be compatible with other extension.
    `static java.util.jar.Attributes.Name` | `SPECIFICATION_VENDOR` Manifest Attribute Name object for SPECIFICATION_VENDOR.
    `static java.util.jar.Attributes.Name` | `SPECIFICATION_VERSION` Manifest Attribute Name object for SPECIFICATION_VERSION.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `Extension(java.lang.String extensionName, java.lang.String specificationVersion, java.lang.String specificationVendor, java.lang.String implementationVersion, java.lang.String implementationVendor, java.lang.String implementationVendorId, java.lang.String implementationURL)` The constructor to create Extension object.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static void` | `addExtension(Extension extension, java.util.jar.Attributes attributes)` Add Extension to the specified manifest Attributes.
    `static void` | `addExtension(Extension extension, java.lang.String prefix, java.util.jar.Attributes attributes)` Add Extension to the specified manifest Attributes.
    `static Extension[]` | `getAvailable(java.util.jar.Manifest manifest)` Return an array of `Extension` objects representing optional packages that are available in the JAR file associated with the specified `Manifest`.
    `Compatibility` | `getCompatibilityWith(Extension required)` Return a Compatibility enum indicating the relationship of this `Extension` with the specified `Extension`.
    `java.lang.String` | `getExtensionName()` Get the name of the extension.
    `java.lang.String` | `getImplementationURL()` Get the url of the extensions implementation.
    `java.lang.String` | `getImplementationVendor()` Get the vendor of the extensions implementation.
    `java.lang.String` | `getImplementationVendorID()` Get the vendorID of the extensions implementation.
    `DeweyDecimal` | `getImplementationVersion()` Get the version of the extensions implementation.
    `static Extension[]` | `getOptions(java.util.jar.Manifest manifest)` Return the set of `Extension` objects representing "Optional Packages" that the application declares they will use if present.
    `static Extension[]` | `getRequired(java.util.jar.Manifest manifest)` Return the set of `Extension` objects representing optional packages that are required by the application contained in the JAR file associated with the specified `Manifest`.
    `java.lang.String` | `getSpecificationVendor()` Get the vendor of the extensions specification.
    `DeweyDecimal` | `getSpecificationVersion()` Get the version of the extensions specification.
    `boolean` | `isCompatibleWith(Extension required)` Return `true` if the specified `Extension` (which represents an optional package required by an application) is satisfied by this `Extension` (which represents an optional package that is already installed.
    `java.lang.String` | `toString()` Return a String representation of this object.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### EXTENSION_LIST

          public static final java.util.jar.Attributes.Name EXTENSION_LIST

      Manifest Attribute Name object for EXTENSION_LIST.

    - #### OPTIONAL_EXTENSION_LIST

          public static final java.util.jar.Attributes.Name OPTIONAL_EXTENSION_LIST

      `Name` object for `Optional-Extension-List` manifest attribute used for declaring optional dependencies on installed extensions. Note that the dependencies declared by this method are not required for the library to operate but if present will be used. It is NOT part of the official "Optional Package" specification.
      See Also:
        Installed extension dependency

    - #### EXTENSION_NAME

          public static final java.util.jar.Attributes.Name EXTENSION_NAME

      Manifest Attribute Name object for EXTENSION_NAME.

    - #### SPECIFICATION_VERSION

          public static final java.util.jar.Attributes.Name SPECIFICATION_VERSION

      Manifest Attribute Name object for SPECIFICATION_VERSION.

    - #### SPECIFICATION_VENDOR

          public static final java.util.jar.Attributes.Name SPECIFICATION_VENDOR

      Manifest Attribute Name object for SPECIFICATION_VENDOR.

    - #### IMPLEMENTATION_VERSION

          public static final java.util.jar.Attributes.Name IMPLEMENTATION_VERSION

      Manifest Attribute Name object for IMPLEMENTATION_VERSION.

    - #### IMPLEMENTATION_VENDOR

          public static final java.util.jar.Attributes.Name IMPLEMENTATION_VENDOR

      Manifest Attribute Name object for IMPLEMENTATION_VENDOR.

    - #### IMPLEMENTATION_URL

          public static final java.util.jar.Attributes.Name IMPLEMENTATION_URL

      Manifest Attribute Name object for IMPLEMENTATION_URL.

    - #### IMPLEMENTATION_VENDOR_ID

          public static final java.util.jar.Attributes.Name IMPLEMENTATION_VENDOR_ID

      Manifest Attribute Name object for IMPLEMENTATION_VENDOR_ID.

    - #### COMPATIBLE

          public static final Compatibility COMPATIBLE

      Enum indicating that extension is compatible with other extension.

    - #### REQUIRE_SPECIFICATION_UPGRADE

          public static final Compatibility REQUIRE_SPECIFICATION_UPGRADE

      Enum indicating that extension requires an upgrade of specification to be compatible with other extension.

    - #### REQUIRE_VENDOR_SWITCH

          public static final Compatibility REQUIRE_VENDOR_SWITCH

      Enum indicating that extension requires a vendor switch to be compatible with other extension.

    - #### REQUIRE_IMPLEMENTATION_UPGRADE

          public static final Compatibility REQUIRE_IMPLEMENTATION_UPGRADE

      Enum indicating that extension requires an upgrade of implementation to be compatible with other extension.

    - #### INCOMPATIBLE

          public static final Compatibility INCOMPATIBLE

      Enum indicating that extension is incompatible with other extension in ways other than other enums indicate). For example the other extension may have a different ID.

  - ### Constructor Detail

    - #### Extension

          public Extension(java.lang.String extensionName,
                           java.lang.String specificationVersion,
                           java.lang.String specificationVendor,
                           java.lang.String implementationVersion,
                           java.lang.String implementationVendor,
                           java.lang.String implementationVendorId,
                           java.lang.String implementationURL)

      The constructor to create Extension object. Note that every component is allowed to be specified but only the extensionName is mandatory.
      Parameters:
        `extensionName` - the name of extension.
        `specificationVersion` - the specification Version of extension.
        `specificationVendor` - the specification Vendor of extension.
        `implementationVersion` - the implementation Version of extension.
        `implementationVendor` - the implementation Vendor of extension.
        `implementationVendorId` - the implementation VendorId of extension.
        `implementationURL` - the implementation URL of extension.

  - ### Method Detail

    - #### getAvailable

          public static Extension[] getAvailable(java.util.jar.Manifest manifest)

      Return an array of `Extension` objects representing optional packages that are available in the JAR file associated with the specified `Manifest`. If there are no such optional packages, a zero-length array is returned.
      Parameters:
        `manifest` - Manifest to be parsed
      Returns:
        the "available" extensions in specified manifest

    - #### getRequired

          public static Extension[] getRequired(java.util.jar.Manifest manifest)

      Return the set of `Extension` objects representing optional packages that are required by the application contained in the JAR file associated with the specified `Manifest`. If there are no such optional packages, a zero-length list is returned.
      Parameters:
        `manifest` - Manifest to be parsed
      Returns:
        the dependencies that are specified in manifest

    - #### getOptions

          public static Extension[] getOptions(java.util.jar.Manifest manifest)

      Return the set of `Extension` objects representing "Optional Packages" that the application declares they will use if present. If there are no such optional packages, a zero-length list is returned.
      Parameters:
        `manifest` - Manifest to be parsed
      Returns:
        the optional dependencies that are specified in manifest

    - #### addExtension

          public static void addExtension(Extension extension,
                                          java.util.jar.Attributes attributes)

      Add Extension to the specified manifest Attributes.
      Parameters:
        `attributes` - the attributes of manifest to add to
        `extension` - the extension

    - #### addExtension

          public static void addExtension(Extension extension,
                                          java.lang.String prefix,
                                          java.util.jar.Attributes attributes)

      Add Extension to the specified manifest Attributes. Use the specified prefix so that dependencies can added with a prefix such as "java3d-" etc.
      Parameters:
        `attributes` - the attributes of manifest to add to
        `extension` - the extension
        `prefix` - the name to prefix to extension

    - #### getExtensionName

          public java.lang.String getExtensionName()

      Get the name of the extension.
      Returns:
        the name of the extension

    - #### getSpecificationVendor

          public java.lang.String getSpecificationVendor()

      Get the vendor of the extensions specification.
      Returns:
        the vendor of the extensions specification.

    - #### getSpecificationVersion

          public DeweyDecimal getSpecificationVersion()

      Get the version of the extensions specification.
      Returns:
        the version of the extensions specification.

    - #### getImplementationURL

          public java.lang.String getImplementationURL()

      Get the url of the extensions implementation.
      Returns:
        the url of the extensions implementation.

    - #### getImplementationVendor

          public java.lang.String getImplementationVendor()

      Get the vendor of the extensions implementation.
      Returns:
        the vendor of the extensions implementation.

    - #### getImplementationVendorID

          public java.lang.String getImplementationVendorID()

      Get the vendorID of the extensions implementation.
      Returns:
        the vendorID of the extensions implementation.

    - #### getImplementationVersion

          public DeweyDecimal getImplementationVersion()

      Get the version of the extensions implementation.
      Returns:
        the version of the extensions implementation.

    - #### getCompatibilityWith

          public Compatibility getCompatibilityWith(Extension required)

      Return a Compatibility enum indicating the relationship of this `Extension` with the specified `Extension`.
      Parameters:
        `required` - Description of the required optional package
      Returns:
        the enum indicating the compatibility (or lack thereof) of specified extension

    - #### isCompatibleWith

          public boolean isCompatibleWith(Extension required)

      Return `true` if the specified `Extension` (which represents an optional package required by an application) is satisfied by this `Extension` (which represents an optional package that is already installed. Otherwise, return `false`.
      Parameters:
        `required` - Description of the required optional package
      Returns:
        true if the specified extension is compatible with this extension

    - #### toString

          public java.lang.String toString()

      Return a String representation of this object.
      Overrides:
        `toString` in class `java.lang.Object`
      Returns:
        string representation of object.