Eclipse Action with Generics

I wrote this code a couple of weeks ago. It’s a nice idea on how to use generics in order to reduce the pain of using the Eclipse API.

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jface.action.IAction;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.ui.IObjectActionDelegate;
import org.eclipse.ui.IWorkbenchPart;

public abstract class TypedAction<T> implements IObjectActionDelegate {

  protected List<T> selectedElements = new ArrayList<T>();
  protected Shell shell;

  public void setActivePart(IAction action, IWorkbenchPart targetPart) {
    this.shell = targetPart.getSite().getShell();
  }

  public void run(IAction action) {
    for (T element : selectedElements) {
      runOn(element, action);
    }
  }

  protected abstract void runOn(T selectedElement, IAction action);

  public void selectionChanged(IAction action, ISelection selection) {
    selectedElements.clear();

    boolean enabled = false;

    if (selection instanceof StructuredSelection) {
      enabled = true;
      for (Iterator it = ((StructuredSelection) selection).iterator(); it.hasNext();) {
        try {
          T selectedElement = (T) it.next();
          selectedElements.add(selectedElement);
        } catch (ClassCastException e) {
          enabled = false;
          break;
        }
      }
    }
    action.setEnabled(enabled);
  }
}

Try to refactor your actions to extend this class and you will find a significant reduction in code size.