UnknownElementException (Java Platform SE 8 )
Keywords: javax.lang.model.element.UnknownElementException class
Date: 2026-04-22

compact3
javax.lang.model.element

## Class UnknownElementException

- java.lang.Object
- - java.lang.Throwable
  - - java.lang.Exception
    - - java.lang.RuntimeException
      - - javax.lang.model.UnknownEntityException
        - - javax.lang.model.element.UnknownElementException

- All Implemented Interfaces:
    Serializable

      public class UnknownElementException
      extends UnknownEntityException

  Indicates that an unknown kind of element was encountered. This can occur if the language evolves and new kinds of elements are added to the `Element` hierarchy. May be thrown by an element visitor to indicate that the visitor was created for a prior version of the language.
  Since:
    1.6
  See Also:
    `ElementVisitor.visitUnknown(javax.lang.model.element.Element, P)`, Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `UnknownElementException(Element e, Object p)` Creates a new `UnknownElementException`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `Object` | `getArgument()` Returns the additional argument.
    `Element` | `getUnknownElement()` Returns the unknown element.

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

      `addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString`

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

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

- - ### Constructor Detail

    - #### UnknownElementException

          public UnknownElementException(Element e,
                                         Object p)

      Creates a new `UnknownElementException`. The `p` parameter may be used to pass in an additional argument with information about the context in which the unknown element was encountered; for example, the visit methods of `ElementVisitor` may pass in their additional parameter.
      Parameters:
        `e` - the unknown element, may be `null`
        `p` - an additional parameter, may be `null`

  - ### Method Detail

    - #### getUnknownElement

          public Element getUnknownElement()

      Returns the unknown element. The value may be unavailable if this exception has been serialized and then read back in.
      Returns:
        the unknown element, or `null` if unavailable

    - #### getArgument

          public Object getArgument()

      Returns the additional argument.
      Returns:
        the additional argument

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