A Java element delta describes changes in Java element between two discrete points in time. Given a delta, clients can access the element that has changed, and any children that have changed.

Deltas have a different status depending on the kind of change they represent. The list below summarizes each status (as returned by getKind) and its meaning (see individual constants for a more detailled description):

• ADDED - The element described by the delta has been added.
• REMOVED - The element described by the delta has been removed.
• CHANGED - The element described by the delta has been changed in some way. Specification of the type of change is provided by getFlags which returns the following values:
  • F_ADDED_TO_CLASSPATH - A classpath entry corresponding to the element has been added to the project's classpath. This flag is only valid if the element is an IPackageFragmentRoot.
  • F_ARCHIVE_CONTENT_CHANGED - The contents of an archive has changed in some way. This flag is only valid if the element is an IPackageFragmentRoot which is an archive.
  • F_CHILDREN - A child of the element has changed in some way. This flag is only valid if the element is an IParent.
  • F_CLASSPATH_REORDER - A classpath entry corresponding to the element has changed position in the project's classpath. This flag is only valid if the element is an IPackageFragmentRoot.
  • F_CLOSED - The underlying IProject has been closed. This flag is only valid if the element is an IJavaProject.
  • F_CONTENT - The contents of the element have been altered. This flag is only valid for elements which correspond to files.
  • F_FINE_GRAINED - The delta is a fine-grained delta, that is, an analysis down to the members level was done to determine if there were structural changes to members of the element.
  • F_MODIFIERS - The modifiers on the element have changed in some way. This flag is only valid if the element is an IMember.
  • F_OPENED - The underlying IProject has been opened. This flag is only valid if the element is an IJavaProject.
  • F_REMOVED_FROM_CLASSPATH - A classpath entry corresponding to the element has been removed from the project's classpath. This flag is only valid if the element is an IPackageFragmentRoot.
  • F_SOURCEATTACHED - The source attachment path or the source attachment root path of a classpath entry corresponding to the element was added. This flag is only valid if the element is an IPackageFragmentRoot.
  • F_SOURCEDETACHED - The source attachment path or the source attachment root path of a classpath entry corresponding to the element was removed. This flag is only valid if the element is an IPackageFragmentRoot.
  • F_SUPER_TYPES - One of the supertypes of an IType has changed
  .

Move operations are indicated by other change flags, layered on top of the change flags described above. If element A is moved to become B, the delta for the change in A will have status REMOVED, with change flag F_MOVED_TO. In this case, getMovedToElement on delta A will return the handle for B. The delta for B will have status ADDED, with change flag F_MOVED_FROM, and getMovedFromElement on delta B will return the handle for A. (Note, the handle to A in this case represents an element that no longer exists).

Note that the move change flags only describe the changes to a single element, they do not imply anything about the parent or children of the element.

The F_ADDED_TO_CLASSPATH, F_REMOVED_FROM_CLASSPATH and F_CLASSPATH_REORDER flags are triggered by changes to a project's classpath. They do not mean that the underlying resource was added, removed or changed. For example, if a project P already contains a folder src, then adding a classpath entry with the 'P/src' path to the project's classpath will result in an IJavaElementDelta with the F_ADDED_TO_CLASSPATH flag for the IPackageFragmentRoot P/src. On the contrary, if a resource is physically added, removed or changed and this resource corresponds to a classpath entry of the project, then an IJavaElementDelta with the ADDED, REMOVED, or CHANGED kind will be fired.

Note that when a source attachment path or a source attachment root path is changed, then the flags of the delta contain both F_SOURCEATTACHED and F_SOURCEDETTACHED.

No assumptions should be made on whether the java element delta tree is rooted at the IJavaModel level or not.

IJavaElementDelta object are not valid outside the dynamic scope of the notification.

This interface is not intended to be implemented by clients.