Java tutorial
/***************************************************************************** * Copyright (c) 2006, 2007 g-Eclipse Consortium * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Initial development of the original code was made for the * g-Eclipse project founded by European Union * project number: FP6-IST-034327 http://www.geclipse.eu/ * * Contributors: * Mathias Stuempert - initial API and implementation *****************************************************************************/ package eu.geclipse.ui.internal; import java.util.ArrayList; import java.util.List; import org.eclipse.core.resources.IResource; import org.eclipse.core.runtime.IAdaptable; import org.eclipse.jface.viewers.ISelection; import org.eclipse.jface.viewers.ISelectionChangedListener; import org.eclipse.jface.viewers.ISelectionProvider; import org.eclipse.jface.viewers.IStructuredSelection; import org.eclipse.jface.viewers.SelectionChangedEvent; import org.eclipse.jface.viewers.StructuredSelection; import eu.geclipse.core.model.IGridElement; /** * Implementation of {@link ISelectionProvider} and {@link ISelectionChangedListener} * that maps a selection of {@link IGridElement}s to a selection of * {@link IResource}s. This adapter may be used wherever only {@link IResource}s * are allowed. */ public class GridElementSelectionAdapter implements ISelectionProvider, ISelectionChangedListener { /** * List of all {@link ISelectionChangedListener} listening * this {@link ISelectionProvider}. */ private List<ISelectionChangedListener> listeners = new ArrayList<ISelectionChangedListener>(); /** * The current selection. */ private ISelection currentSelection; /* (non-Javadoc) * @see org.eclipse.jface.viewers.ISelectionProvider#addSelectionChangedListener(org.eclipse.jface.viewers.ISelectionChangedListener) */ public void addSelectionChangedListener(final ISelectionChangedListener listener) { if (!this.listeners.contains(listener)) { this.listeners.add(listener); } } /* (non-Javadoc) * @see org.eclipse.jface.viewers.ISelectionProvider#getSelection() */ public ISelection getSelection() { return this.currentSelection == null ? StructuredSelection.EMPTY : this.currentSelection; } /* (non-Javadoc) * @see org.eclipse.jface.viewers.ISelectionProvider#removeSelectionChangedListener(org.eclipse.jface.viewers.ISelectionChangedListener) */ public void removeSelectionChangedListener(final ISelectionChangedListener listener) { this.listeners.remove(listener); } /* (non-Javadoc) * @see org.eclipse.jface.viewers.ISelectionChangedListener#selectionChanged(org.eclipse.jface.viewers.SelectionChangedEvent) */ public void selectionChanged(final SelectionChangedEvent event) { setSelection(event.getSelection()); } /* (non-Javadoc) * @see org.eclipse.jface.viewers.ISelectionProvider#setSelection(org.eclipse.jface.viewers.ISelection) */ public void setSelection(final ISelection selection) { if (selection instanceof IStructuredSelection) { setSelection((IStructuredSelection) selection); } } /** * Sets the current selection and notifies all {@link ISelectionChangedListener}s * that the selection has changed. * * @param selection The new {@link IStructuredSelection}. */ public void setSelection(final IStructuredSelection selection) { this.currentSelection = remapSelection(selection); fireSelectionChanged(); } /** * Notifies all registered {@link ISelectionChangedListener}s * that the current selection has changed. */ protected void fireSelectionChanged() { SelectionChangedEvent event = new SelectionChangedEvent(this, getSelection()); for (ISelectionChangedListener listener : this.listeners) { listener.selectionChanged(event); } } /** * Construct a new selection from the specified selection. The newly * created selection is guaranteed to only contain {@link IResource}s. * If no {@link IResource} can be created from a element of the original * selection this element will not be contained in the newly created * selection. So it may happen that even if the specified selection * is not empty the returned selection may be empty. * * @param selection The selection to be remapped. * @return A new selection that only holds {@link IResource}s. */ protected IStructuredSelection remapSelection(final IStructuredSelection selection) { List<IResource> resources = new ArrayList<IResource>(); for (Object o : selection.toList()) { IResource resource = remapObject(o); if (resource != null) { resources.add(resource); } } return new StructuredSelection(resources); } /** * Get an {@link IResource} from the specified {@link IGridElement}. * * @param e The element to be remapped. * @return An {@link IResource} or <code>null</code> if no * {@link IResource} could be retrieved from the specified element. * @see IGridElement#getResource() */ private IResource remapGridElement(final IGridElement e) { return e.getResource(); } /** * Remap the specified object to an {@link IResource} if possible. * This method first checks if the specified object already is an * {@link IResource}. In that case the original object is just casted * and returned. Furthermore the object is tested if it is an * {@link IGridElement}. In that case {@link #remapGridElement(IGridElement)} * is called. In all other cases it is tested if the object is an * instance of {@link IAdaptable}. If all this fails <code>null</code> * will be returned. * * @param o The object to be remapped. * @return An {@link IResource} or <code>null</code> if the object * could not be remapped. */ private IResource remapObject(final Object o) { IResource resource = null; if (o instanceof IResource) { resource = (IResource) o; } else if (o instanceof IGridElement) { resource = remapGridElement((IGridElement) o); } else if (o instanceof IAdaptable) { resource = (IResource) ((IAdaptable) o).getAdapter(IResource.class); } return resource; } }