How to use org.eclipse.ui

 IEditorPart  editorPart =
getSite().getWorkbenchWindow().getActivePage().getActiveEditor();

if(editorPart  != null)
{
  IFileEditorInput input = (IFileEditorInput)editorPart.getEditorInput() ;
  IFile file = input.getFile();
  IProject activeProject = file.getProject();
  String activeProjectName = activeProject.getName();
  //... use activeProjectName 
}

/** Gets the active workbench window. */
public static IWorkbenchWindow getActiveWorkbenchWindow() {
  return PlatformUI.getWorkbench().getActiveWorkbenchWindow();
}
 

 IWorkbenchWindow window =
  PlatformUI.getWorkbench().getActiveWorkbenchWindow();
ISelection selection = window.getSelectionService().getSelection("org.eclipse.jdt.ui.PackageExplorer");

private IEditorPart getActiveEditor()
{
 IWorkbench workbench = PlatformUI.getWorkbench();
 IWorkbenchWindow workbenchWindow = workbench.getActiveWorkbenchWindow();
 IEditorPart editorPart = workbenchWindow.getActivePage().getActiveEditor();
 return editorPart;
}    

@Override
public boolean performOk() {
  IWorkbenchPage activePage = PlatformUI.getWorkbench()
                     .getActiveWorkbenchWindow()
                     .getActivePage();
    Map<IEditorInput, String> editorsToReopen =
      new HashMap<IEditorInput, String>();
    for (IEditorReference editor : activePage.getEditorReferences()) {
      String id = editor.getId();
        editorsToReopen.put(editor.getEditorInput(), id);
      activePage.closeEditors(editorsToClose.toArray(
        new IEditorReference[editorsToClose.size()]), true);
      colorThemeManager.applyTheme(selectedThemeName);
      for (IEditorInput editorInput : editorsToReopen.keySet())
        activePage.openEditor(editorInput, editorsToReopen.get(editorInput));
    e.printStackTrace();

@Override
public void linkingFocusLost(LinkedPosition position, LinkedModeUITarget target) {
  // mark navigation history
  IWorkbenchWindow win= PlatformUI.getWorkbench().getActiveWorkbenchWindow();
  if (win != null) {
    IWorkbenchPage page= win.getActivePage();
    if (page != null) {
      IEditorPart part= page.getActiveEditor();
      page.getNavigationHistory().markLocation(part);
    }
  }
}

  public void run()
  {
    PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().activate(_sqlEditor);
  }
}

public ISelection getSelection() {
  IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
  if (window != null && window.getSelectionService() != null) {
    return window.getSelectionService().getSelection();
  }
  return null;
}

public void dispose() {
  if (fWorkingSetManagerListener != null) {
    PlatformUI.getWorkbench().getWorkingSetManager().removePropertyChangeListener(fWorkingSetManagerListener);
    fLocalWorkingSetManager.removePropertyChangeListener(fWorkingSetManagerListener);
    fLocalWorkingSetManager.dispose();
    fWorkingSetManagerListener= null;
  }
}

private static String getEditorId(String fileName, IContentType type) {
  IEditorRegistry registry = PlatformUI.getWorkbench().getEditorRegistry();
  IEditorDescriptor descriptor = registry.getDefaultEditor(fileName, type);
  String id;
  if (descriptor == null || descriptor.isOpenExternal()) {
    id = "org.eclipse.ui.DefaultTextEditor"; //$NON-NLS-1$
  } else {
    id = descriptor.getId();
  }
  return id;
}

  @Override
  public Image getColumnImage(Object obj, int index) {
    ISharedImages sharedImages = PlatformUI.getWorkbench().getSharedImages();
    return sharedImages.getImage(ISharedImages.IMG_OBJ_FOLDER);
  }
}

/**
 * Returns the status line manager of the active editor.
 * @return the status line manager of the active editor
 */
private IStatusLineManager getStatusLineManager() {
  IEditorPart editor= fWorkbenchPart.getSite().getPage().getActiveEditor();
  if (editor == null)
    return null;
  return editor.getEditorSite().getActionBars().getStatusLineManager();
}

/**
 * @see IPartListener#partClosed(IWorkbenchPart)
 */
public void partClosed(IWorkbenchPart part)
{
  if (part == _fEditor)
  {
    _fEditor.getSite().getWorkbenchWindow().getPartService().removePartListener(_fPartListener);
    _fPartListener = null;
  }
}

/** Gets the active workbench shell. */
public static Shell getActiveWorkbenchShell() {
  IWorkbenchWindow window = getActiveWorkbenchWindow();
  if(window != null) {
    return window.getShell();
  }
  return null;
}
 

private IEditorPart getActiveEditor()
{
 IWorkbench workbench = PlatformUI.getWorkbench();
 IWorkbenchWindow workbenchWindow = workbench.getActiveWorkbenchWindow();
 IEditorPart editorPart = workbenchWindow.getActivePage().getActiveEditor();
 return editorPart;
}    

public void dispose() {
  if (fWorkingSetManagerListener != null) {
    PlatformUI.getWorkbench().getWorkingSetManager().removePropertyChangeListener(fWorkingSetManagerListener);
    fLocalWorkingSetManager.removePropertyChangeListener(fWorkingSetManagerListener);
    fLocalWorkingSetManager.dispose();
    fWorkingSetManagerListener= null;
  }
}

IWorkbenchWindow window = PlatformUI.getWorkbench().getActiveWorkbenchWindow();
 if (window != null)
 {
   IStructuredSelection selection = (IStructuredSelection) window.getSelectionService().getSelection();
   Object firstElement = selection.getFirstElement();
   if (firstElement instanceof IAdaptable)
   {
     IProject project = (IProject)((IAdaptable)firstElement).getAdapter(IProject.class);
     IPath path = project.getFullPath();
     System.out.println(path);
   }
 }

private ITextEditor getActiveEditor() {
  IWorkbenchWindow window= PlatformUI.getWorkbench().getActiveWorkbenchWindow();
  if (window != null) {
    IWorkbenchPage page= window.getActivePage();
    if (page != null) {
      IEditorPart editor= page.getActiveEditor();
      if (editor instanceof ITextEditor)
        return (JavaEditor) editor;
    }
  }
  return null;
}

private ITextEditor getActiveEditor() {
  IWorkbenchWindow window= PlatformUI.getWorkbench().getActiveWorkbenchWindow();
  if (window != null) {
    IWorkbenchPage page= window.getActivePage();
    if (page != null) {
      IEditorPart editor= page.getActiveEditor();
      if (editor instanceof ITextEditor)
        return (JavaEditor) editor;
    }
  }
  return null;
}

private ITextEditor getActiveEditor() {
  IWorkbenchWindow window= PlatformUI.getWorkbench().getActiveWorkbenchWindow();
  if (window != null) {
    IWorkbenchPage page= window.getActivePage();
    if (page != null) {
      IEditorPart editor= page.getActiveEditor();
      if (editor instanceof ITextEditor)
        return (JavaEditor) editor;
    }
  }
  return null;
}