How to use

fireSelectionChanged

method

in

org.eclipse.jface.text.TextViewer

/**
 * Sends out a text selection changed event to all registered listeners and
 * registers the selection changed event to be sent out to all post selection
 * listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 */
protected void selectionChanged(int offset, int length) {
  queuePostSelectionChanged(true);
  fireSelectionChanged(offset, length);
}

/**
 * Sends out a text selection changed event to all registered listeners and
 * registers the selection changed event to be sent out to all post selection
 * listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 */
protected void selectionChanged(int offset, int length) {
  queuePostSelectionChanged(true);
  fireSelectionChanged(offset, length);
}

private void delete() {
  if (!fTextWidget.getBlockSelection()) {
    fTextWidget.invokeAction(ST.DELETE_NEXT);
  } else {
    wrapCompoundChange(new Runnable(){
      @Override
      public void run() {
        try {
          new SelectionProcessor(TextViewer.this).doDelete(getSelection());
        } catch (BadLocationException e) {
          if (TRACE_ERRORS)
            System.out.println(JFaceTextMessages.getString("TextViewer.error.bad_location.delete")); //$NON-NLS-1$
        }
      }
    });
  }
  Point selection= fTextWidget.getSelectionRange();
  fireSelectionChanged(selection.x, selection.y);
}

fireSelectionChanged(selection.x, selection.y);

fireSelectionChanged(selection.x, selection.y);

/**
 * Sends out a text selection changed event to all registered listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 * @since 3.0
 */
protected void fireSelectionChanged(int offset, int length) {
  if (redraws()) {
    if (length < 0) {
      length= -length;
      offset= offset + length;
    }
    IRegion r= widgetRange2ModelRange(new Region(offset, length));
    if ((r != null && !r.equals(fLastSentSelectionChange)) || r == null)  {
      fLastSentSelectionChange= r;
      ISelection selection= r != null ? new TextSelection(getDocument(), r.getOffset(), r.getLength()) : TextSelection.emptySelection();
      SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
      fireSelectionChanged(event);
    }
  }
}

private void delete() {
  if (!fTextWidget.getBlockSelection()) {
    fTextWidget.invokeAction(ST.DELETE_NEXT);
  } else {
    wrapCompoundChange(() -> {
      try {
        new SelectionProcessor(TextViewer.this).doDelete(getSelection());
      } catch (BadLocationException e) {
        if (TRACE_ERRORS)
          System.out.println(JFaceTextMessages.getString("TextViewer.error.bad_location.delete")); //$NON-NLS-1$
      }
    });
  }
  Point selection= fTextWidget.getSelectionRange();
  fireSelectionChanged(selection.x, selection.y);
}

/**
 * Sends out a text selection changed event to all registered listeners.
 *
 * @param offset the offset of the newly selected range in the visible document
 * @param length the length of the newly selected range in the visible document
 * @since 3.0
 */
protected void fireSelectionChanged(int offset, int length) {
  if (redraws()) {
    if (length < 0) {
      length= -length;
      offset= offset + length;
    }
    IRegion r= widgetRange2ModelRange(new Region(offset, length));
    if ((r != null && !r.equals(fLastSentSelectionChange)) || r == null)  {
      fLastSentSelectionChange= r;
      ISelection selection= r != null ? new TextSelection(getDocument(), r.getOffset(), r.getLength()) : TextSelection.emptySelection();
      SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
      fireSelectionChanged(event);
    }
  }
}

/**
 * Sends out a mark selection changed event to all registered listeners.
 *
 * @param offset the offset of the mark selection in the visible document, the offset is <code>-1</code> if the mark was cleared
 * @param length the length of the mark selection, may be negative if the caret is before the mark.
 * @since 2.0
 */
protected void markChanged(int offset, int length) {
  if (redraws()) {
    if (offset != -1) {
      IRegion r= widgetRange2ModelRange(new Region(offset, length));
      offset= r.getOffset();
      length= r.getLength();
    }
    ISelection selection= new MarkSelection(getDocument(), offset, length);
    SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
    fireSelectionChanged(event);
  }
}

/**
 * Sends out a mark selection changed event to all registered listeners.
 *
 * @param offset the offset of the mark selection in the visible document, the offset is <code>-1</code> if the mark was cleared
 * @param length the length of the mark selection, may be negative if the caret is before the mark.
 * @since 2.0
 */
protected void markChanged(int offset, int length) {
  if (redraws()) {
    if (offset != -1) {
      IRegion r= widgetRange2ModelRange(new Region(offset, length));
      offset= r.getOffset();
      length= r.getLength();
    }
    ISelection selection= new MarkSelection(getDocument(), offset, length);
    SelectionChangedEvent event= new SelectionChangedEvent(this, selection);
    fireSelectionChanged(event);
  }
}

fireSelectionChanged(selection.x, selection.y);
if (fLastSentSelectionChange != null) {
  ISelection lastSelection= new TextSelection(getDocument(), fLastSentSelectionChange.getOffset(), fLastSentSelectionChange.getLength());
  fireSelectionChanged(new SelectionChangedEvent(this, lastSelection));

fireSelectionChanged(selection.x, selection.y);
if (fLastSentSelectionChange != null) {
  ISelection lastSelection= new TextSelection(getDocument(), fLastSentSelectionChange.getOffset(), fLastSentSelectionChange.getLength());
  fireSelectionChanged(new SelectionChangedEvent(this, lastSelection));