Package org.eclipse.ui.progress

Class DeferredTreeContentManager

java.lang.Object
org.eclipse.ui.progress.DeferredTreeContentManager
public class DeferredTreeContentManager extends Object
The DeferredContentManager is a class that helps an ITreeContentProvider get its deferred input. NOTE AbstractTreeViewer#isExpandable may need to be implemented in AbstractTreeViewer subclasses with deferred content that use filtering as a call to #getChildren may be required to determine the correct state of the expanding control. AbstractTreeViewers which use this class may wish to sacrifice accuracy of the expandable state indicator for the performance benefits of deferring content.
Since:
3.0
See Also:

  • Constructor Details

    • DeferredTreeContentManager

      @Deprecated(forRemoval=true, since="2025-03") public DeferredTreeContentManager(ITreeContentProvider provider, AbstractTreeViewer viewer, IWorkbenchPartSite site)
      Deprecated, for removal: This API element is subject to removal in a future version.
      in 3.4. provider is not used by this class
      Create a new instance of the receiver using the supplied content provider and viewer. Run any jobs using the site.
      Parameters:
      provider - content provider
      viewer - content viewer
      site - part site

    • DeferredTreeContentManager

      @Deprecated(forRemoval=true, since="2025-03") public DeferredTreeContentManager(ITreeContentProvider provider, AbstractTreeViewer viewer)
      Deprecated, for removal: This API element is subject to removal in a future version.
      in 3.4. provider is not used by this class
      Create a new instance of the receiver using the supplied content provider and viewer.
      Parameters:
      provider - The content provider that will be updated
      viewer - The tree viewer that the results are added to

    • DeferredTreeContentManager

      public DeferredTreeContentManager(AbstractTreeViewer viewer, IWorkbenchPartSite site)
      Create a new instance of the receiver using the supplied content provider and viewer. Run any jobs using the site.
      Parameters:
      viewer - content viewer
      site - part site
      Since:
      3.4

    • DeferredTreeContentManager

      public DeferredTreeContentManager(AbstractTreeViewer viewer)
      Create a new instance of the receiver using the supplied content provider and viewer.
      Parameters:
      viewer - The tree viewer that the results are added to
      Since:
      3.4

  • Method Details

    • mayHaveChildren

      public boolean mayHaveChildren(Object element)
      Provides an optimized lookup for determining if an element has children. This is required because elements that are populated lazilly can't answer getChildren just to determine the potential for children. Throw an AssertionFailedException if element is null.
      Parameters:
      element - The Object being tested. This should not be null.
      Returns:
      boolean true if there are potentially children.
      Throws:
      RuntimeException - if the element is null.

    • getChildren

      public Object[] getChildren(Object parent)
      Returns the child elements of the given element, or in the case of a deferred element, returns a placeholder. If a deferred element is used, a job is created to fetch the children in the background.
      Parameters:
      parent - The parent object.
      Returns:
      Object[] or null if parent is not an instance of IDeferredWorkbenchAdapter.

    • createPendingUpdateAdapter

      protected PendingUpdateAdapter createPendingUpdateAdapter()
      Factory method for creating the pending update adapter representing the placeholder node. Subclasses may override.
      Returns:
      a pending update adapter
      Since:
      3.2

    • getAdapter

      protected IDeferredWorkbenchAdapter getAdapter(Object element)
      Return the IDeferredWorkbenchAdapter for element or the element if it is an instance of IDeferredWorkbenchAdapter. If it does not exist return null.
      Parameters:
      element - element to adapt
      Returns:
      IDeferredWorkbenchAdapter or null

    • startFetchingDeferredChildren

      protected void startFetchingDeferredChildren(Object parent, IDeferredWorkbenchAdapter adapter, PendingUpdateAdapter placeholder)
      Starts a job and creates a collector for fetching the children of this deferred adapter. If children are waiting to be retrieved for this parent already, that job is cancelled and another is started.
      Parameters:
      parent - The parent object being filled in,
      adapter - The adapter being used to fetch the children.
      placeholder - The adapter that will be used to indicate that results are pending.

    • getFetchJobName

      protected String getFetchJobName(Object parent, IDeferredWorkbenchAdapter adapter)
      Returns a name to use for the job that fetches children of the given parent. Subclasses may override. Default job name is parent's label.
      Parameters:
      parent - parent that children are to be fetched for
      adapter - parent's deferred adapter
      Returns:
      job name

    • addChildren

      protected void addChildren(Object parent, Object[] children, IProgressMonitor monitor)
      Create a UIJob to add the children to the parent in the tree viewer.
      Parameters:
      parent - the parent object being filled in
      children - the elements being added
      monitor - a progress monitor

    • isDeferredAdapter

      public boolean isDeferredAdapter(Object element)
      Return whether or not the element is or adapts to an IDeferredWorkbenchAdapter.
      Parameters:
      element - the element to test
      Returns:
      boolean true if the element is an IDeferredWorkbenchAdapter

    • runClearPlaceholderJob

      protected void runClearPlaceholderJob(PendingUpdateAdapter placeholder)
      Run a job to clear the placeholder. This is used when the update for the tree is complete so that the user is aware that no more updates are pending.
      Parameters:
      placeholder - placeholder to clear

    • cancel

      public void cancel(Object parent)
      Cancel all jobs that are fetching content for the given parent or any of its children.
      Parameters:
      parent - the root to cancel

    • createElementCollector

      protected IElementCollector createElementCollector(Object parent, PendingUpdateAdapter placeholder)
      Create the element collector for the receiver.
      Parameters:
      parent - The parent object being filled in,
      placeholder - The adapter that will be used to indicate that results are pending.
      Returns:
      IElementCollector

    • addUpdateCompleteListener

      public void addUpdateCompleteListener(IJobChangeListener listener)
      Add a listener to list of update complete listeners. These listeners are attached to the job that updates the viewer content (clears the pending entry, etc.) after all deferred content has been retrieved. This method has no effect if the listener has already been added to the list of listeners. Since 3.6, this listener is added to a list of listeners rather than replacing the previously added listener. For backward compatibility, adding a null listener will be interpreted as removal of a listener if only one listener has been registered.
      Parameters:
      listener - the listener to add to the list of update listeners
      Since:
      3.4

    • removeUpdateCompleteListener

      public void removeUpdateCompleteListener(IJobChangeListener listener)
      Removes the listener from the list of update listeners that are attached to the job that updates the viewer content (clears the pending entry, etc.) after all deferred content has been retrieved. If the listener is already attached to a running job, it is not removed, but it will not be added to any subsequent jobs that are run. This method has no effect if the listener was not previously added to the listener list.
      Parameters:
      listener - the listener to be removed
      Since:
      3.6