Code example for LinkedList

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import com.google.refine.freebase.FreebaseType; 
import com.google.refine.model.OverlayModel; 
import com.google.refine.model.Project; 
 
public class Protograph implements OverlayModel { 
    final protected List<Node> _rootNodes = new LinkedList<Node>();
     
    public int getRootNodeCount() { 
        return _rootNodes.size();
    } 
     
    public Node getRootNode(int index) {
        return _rootNodes.get(index);
    } 
     
    @Override 
    public void onBeforeSave(Project project) {
    } 
     
    @Override 
    public void onAfterSave(Project project) {