Package net.sf.saxon.value

Class ObjectValue<T>

java.lang.Object
net.sf.saxon.value.ObjectValue<T>
All Implemented Interfaces:
GroundedValue, Item, Sequence, AnyExternalObject
Direct Known Subclasses:
Bindery.FailureValue, MemoFunction.NodeSurrogate, Tuple
public class ObjectValue<T> extends Object implements AnyExternalObject
An XPath value that encapsulates a Java object. Such a value can only be constructed from Java code either in a Java extension function, or in the calling application.

Until Saxon 9.4, ObjectValue was a subclass of AtomicValue, and external Java objects were considered to be atomic. From 9.5, this has been changed so that an ObjectValue is another kind of Item: a fourth kind, at the same level as nodes, atomic values, and function items.

In the same way as ObjectValue is a wrapper around a Java instance object, the type of the value is a wrapper around the corresponding Java class. These types have subtype-supertype relationships that correspond to the Java class hierarchy. The top type in this branch of the class hierarchy, which wraps the Java class "Object", has item() as its superclass. These types can be referred to in the SequenceType syntax using QNames of the form jt:full.package.name.ClassName, where the conventional prefix jt maps to the namespace URI http://saxon.sf.net/java-type.

An ObjectValue is no longer permitted to wrap a Java null. An empty sequence should be used in this situation.

The effective boolean value of a wrapped Java object, like that of a node, is always true.

Atomizing a wrapped Java object, or applying the fn:string() function, returns an xs:string whose value is the result of calling toString() on the wrapped Java object.

  • Constructor Details

    • ObjectValue

      public ObjectValue(T object)
      Constructor
      Parameters:
      object - the object to be encapsulated

    • ObjectValue

      public ObjectValue(T object, Class<? extends T> theInterface)

  • Method Details

    • getInterface

      public Class<? extends T> getInterface()

    • getGenre

      public Genre getGenre()
      Get the genre of this item
      Specified by:
      getGenre in interface Item
      Returns:
      the genre

    • getUnicodeStringValue

      public UnicodeString getUnicodeStringValue()
      Get the value of the item as a string. For nodes, this is the string value of the node as defined in the XPath 2.0 data model, except that all nodes are treated as being untyped: it is not an error to get the string value of a node with a complex type. For atomic values, the method returns the result of casting the atomic value to a string.
      Specified by:
      getUnicodeStringValue in interface GroundedValue
      Specified by:
      getUnicodeStringValue in interface Item
      Returns:
      the string value of the item
      Throws:
      UnsupportedOperationException - if the item is a function item (an unchecked exception is used here to avoid introducing exception handling to a large number of paths where it is not needed)
      Since:
      8.4

    • atomize

      public StringValue atomize()
      Atomize the item.
      Specified by:
      atomize in interface Item
      Returns:
      the result of atomization. For an external object this is defined to be the result of the toString() method, as an xs:string value.

    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Determine the data type of the items in the expression, if possible
      Specified by:
      getItemType in interface AnyExternalObject
      Parameters:
      th - The TypeHierarchy.
      Returns:
      for the default implementation: AnyItemType (not known)

    • displayTypeName

      public static String displayTypeName(Object value)
      Display the type name for use in error messages
      Parameters:
      value - a Java object
      Returns:
      the type name. This will be in the form "java-type:" followed by the full class name of the wrapped Java object.

    • effectiveBooleanValue

      public boolean effectiveBooleanValue()
      Get the effective boolean value of the value
      Specified by:
      effectiveBooleanValue in interface GroundedValue
      Returns:
      true (always)

    • getObject

      public T getObject()
      Get the encapsulated object
      Returns:
      the Java object that this external object wraps

    • getWrappedObject

      public Object getWrappedObject()
      Get the encapsulated object. This version of the method does not use generics, enabling it to work the same way in Java and C#.
      Specified by:
      getWrappedObject in interface AnyExternalObject
      Returns:
      the Java object that this external object wraps

    • equals

      public boolean equals(Object other)
      Determine if two ObjectValues are equal
      Overrides:
      equals in class Object
      Returns:
      true if the other object is also a wrapped Java object and if the two wrapped objects compare equal using the Java equals() method.

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toShortString

      public String toShortString()
      Description copied from interface: Item
      Provide a short string showing the contents of the item, suitable for use in error messages
      Specified by:
      toShortString in interface GroundedValue
      Specified by:
      toShortString in interface Item
      Returns:
      a depiction of the item suitable for use in error messages