org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageFragmentProvider.java - jdt/eclipse.jdt.ui - Git at Google

 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * 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
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.jdt.internal.ui.packageview;

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

 import org.eclipse.core.runtime.CoreException;

 import org.eclipse.core.resources.IFolder;
 import org.eclipse.core.resources.IResource;

 import org.eclipse.swt.widgets.Control;
 import org.eclipse.swt.widgets.Display;

 import org.eclipse.jface.util.IPropertyChangeListener;
 import org.eclipse.jface.util.PropertyChangeEvent;
 import org.eclipse.jface.viewers.TreeViewer;
 import org.eclipse.jface.viewers.Viewer;

 import org.eclipse.jdt.core.ElementChangedEvent;
 import org.eclipse.jdt.core.IJavaElement;
 import org.eclipse.jdt.core.IJavaElementDelta;
 import org.eclipse.jdt.core.IJavaProject;
 import org.eclipse.jdt.core.IPackageFragment;
 import org.eclipse.jdt.core.IPackageFragmentRoot;
 import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.core.JavaModelException;

 import org.eclipse.jdt.ui.PreferenceConstants;

 import org.eclipse.jdt.internal.ui.JavaPlugin;

 /**
  * Content provider which provides package fragments for hierarchical
  * Package Explorer layout.
  *
  * @since 2.1
  */
 public class PackageFragmentProvider implements IPropertyChangeListener {

 	private TreeViewer fViewer;
 	private boolean fFoldPackages;

 	public PackageFragmentProvider() {
 		fFoldPackages= arePackagesFoldedInHierarchicalLayout();
 		JavaPlugin.getDefault().getPreferenceStore().addPropertyChangeListener(this);
 	}

 	/*
 	 * @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(Object)
 	 */
 	public Object[] getChildren(Object parentElement) {
 		try {
 			if (parentElement instanceof IFolder) {
 				IResource[] resources= ((IFolder) parentElement).members();
 				return filter(getFolders(resources)).toArray();
 			} else if (parentElement instanceof IJavaElement) {
 				IJavaElement iJavaElement= (IJavaElement) parentElement;
 				int type= iJavaElement.getElementType();

 				switch (type) {
 					case IJavaElement.JAVA_PROJECT: {
 						IJavaProject project= (IJavaProject) iJavaElement;

 						IPackageFragmentRoot root= project.findPackageFragmentRoot(project.getPath());
 						if (root != null) {
 							List children= getTopLevelChildren(root);
 							return filter(children).toArray();
 						}
 						break;
 					}
 					case IJavaElement.PACKAGE_FRAGMENT_ROOT: {
 						IPackageFragmentRoot root= (IPackageFragmentRoot) parentElement;
 						if (root.exists()) {
 							return filter(getTopLevelChildren(root)).toArray();
 						}
 						break;
 					}
 					case IJavaElement.PACKAGE_FRAGMENT: {
 						IPackageFragment packageFragment = (IPackageFragment) parentElement;
 						if (!packageFragment.isDefaultPackage()) {
 							IPackageFragmentRoot root= (IPackageFragmentRoot) packageFragment.getParent();
 							List children = getPackageChildren(root, packageFragment);
 							return filter(children).toArray();
 						}
 						break;
 					}
 					default :
 						// do nothing
 				}
 			}
 		} catch (CoreException e) {
 			JavaPlugin.log(e);
 		}
 		return new Object[0];
 	}

 	private List filter(List children) throws JavaModelException {
 		if (fFoldPackages) {
 			int size= children.size();
 			for (int i = 0; i < size; i++) {
 				Object curr= children.get(i);
 				if (curr instanceof IPackageFragment) {
 					IPackageFragment fragment = (IPackageFragment) curr;
 					if (!fragment.isDefaultPackage() && isEmpty(fragment)) {
 						IPackageFragment collapsed= getCollapsed(fragment);
 						if (collapsed != null) {
 							children.set(i, collapsed); // replace with collapsed
 						}
 					}
 				}
 			}
 		}
 		return children;
 	}

 	private IPackageFragment getCollapsed(IPackageFragment pack) throws JavaModelException {
 		IJavaElement[] children= ((IPackageFragmentRoot) pack.getParent()).getChildren();
 		IPackageFragment child= getSinglePackageChild(pack, children);
 		while (child != null && isEmpty(child)) {
 			IPackageFragment collapsed= getSinglePackageChild(child, children);
 			if (collapsed == null) {
 				return child;
 			}
 			child= collapsed;
 		}
 		return child;
 	}

 	private boolean isEmpty(IPackageFragment fragment) throws JavaModelException {
 		return !fragment.containsJavaResources() && fragment.getNonJavaResources().length == 0;
 	}

 	private static IPackageFragment getSinglePackageChild(IPackageFragment fragment, IJavaElement[] children) {
 		String prefix= fragment.getElementName() + '.';
 		int prefixLen= prefix.length();
 		IPackageFragment found= null;
 		for (int i= 0; i < children.length; i++) {
 			IJavaElement element= children[i];
 			String name= element.getElementName();
 			if (name.startsWith(prefix) && name.length() > prefixLen && name.indexOf('.', prefixLen) == -1) {
 				if (found == null) {
 					found= (IPackageFragment) element;
 				} else {
 					return null;
 				}
 			}
 		}
 		return found;
 	}


 	private static List getPackageChildren(IPackageFragmentRoot parent, IPackageFragment fragment) throws JavaModelException {
 		IJavaElement[] children= parent.getChildren();
 		ArrayList list= new ArrayList(children.length);
 		String prefix= fragment.getElementName() + '.';
 		int prefixLen= prefix.length();
 		for (int i= 0; i < children.length; i++) {
 			IJavaElement element= children[i];
 			if (element instanceof IPackageFragment) { // see bug 134256
 				String name= element.getElementName();
 				if (name.startsWith(prefix) && name.length() > prefixLen && name.indexOf('.', prefixLen) == -1) {
 					list.add(element);
 				}
 			}
 		}
 		return list;
 	}

 	private static List getTopLevelChildren(IPackageFragmentRoot root) throws JavaModelException {
 		IJavaElement[] elements= root.getChildren();
 		ArrayList topLevelElements= new ArrayList(elements.length);
 		for (int i= 0; i < elements.length; i++) {
 			IJavaElement iJavaElement= elements[i];
 			//if the name of the PackageFragment is the top level package it will contain no "." separators
 			if (iJavaElement instanceof IPackageFragment && iJavaElement.getElementName().indexOf('.')==-1) {
 				topLevelElements.add(iJavaElement);
 			}
 		}
 		return topLevelElements;
 	}

 	private List getFolders(IResource[] resources) throws JavaModelException {
 		List list= new ArrayList(resources.length);
 		for (int i= 0; i < resources.length; i++) {
 			IResource resource= resources[i];
 			if (resource instanceof IFolder) {
 				IFolder folder= (IFolder) resource;
 				IJavaElement element= JavaCore.create(folder);
 				if (element instanceof IPackageFragment) {
 					list.add(element);
 				}
 			}
 		}
 		return list;
 	}


 	/*
 	 * @see org.eclipse.jface.viewers.ITreeContentProvider#getParent(Object)
 	 */
 	public Object getParent(Object element) {

 		if (element instanceof IPackageFragment) {
 			IPackageFragment frag = (IPackageFragment) element;
 			//@Changed: a fix, before: if(frag.exists() && isEmpty(frag))

 			return filterParent(getActualParent(frag));
 		}
 		return null;
 	}

 	private Object getActualParent(IPackageFragment fragment) {
 		try {

 			if (fragment.exists()) {
 				IJavaElement parent = fragment.getParent();

 				if ((parent instanceof IPackageFragmentRoot) && parent.exists()) {
 					IPackageFragmentRoot root = (IPackageFragmentRoot) parent;
 					if (root.isArchive()) {
 						return findNextLevelParentByElementName(fragment);
 					} else {

 						IResource resource = fragment.getUnderlyingResource();
 						if ((resource != null) && (resource instanceof IFolder)) {
 							IFolder folder = (IFolder) resource;
 							IResource res = folder.getParent();

 							IJavaElement el = JavaCore.create(res);
 							if (el != null) {
 								return el;
 							} else {
 								return res;
 							}
 						}
 					}
 					return parent;
 				}
 			}

 		} catch (JavaModelException e) {
 			JavaPlugin.log(e);
 		}
 		return null;
 	}

 	private Object filterParent(Object parent) {
 		if (fFoldPackages && (parent!=null)) {
 			try {
 				if (parent instanceof IPackageFragment) {
 					IPackageFragment fragment = (IPackageFragment) parent;
 					if (isEmpty(fragment) && hasSingleChild(fragment)) {
 						return filterParent(getActualParent(fragment));
 					}
 				}
 			} catch (JavaModelException e) {
 				JavaPlugin.log(e);
 			}
 		}
 		return parent;
 	}

 	private boolean hasSingleChild(IPackageFragment fragment) {
 		return getChildren(fragment).length==1;
 	}


 	private Object findNextLevelParentByElementName(IPackageFragment child) {
 		String name= child.getElementName();

 		int index= name.lastIndexOf('.');
 		if (index != -1) {
 			String realParentName= name.substring(0, index);
 			IPackageFragment element= ((IPackageFragmentRoot) child.getParent()).getPackageFragment(realParentName);
 			if (element.exists()) {
 				return element;
 			}
 		}
 		return child.getParent();
 	}


 	/*
 	 * @see org.eclipse.jface.viewers.ITreeContentProvider#hasChildren(Object)
 	 */
 	public boolean hasChildren(Object element) {

 		if (element instanceof IPackageFragment) {
 			IPackageFragment fragment= (IPackageFragment) element;
 			if(fragment.isDefaultPackage())
 				return false;
 		}
 		return getChildren(element).length > 0;
 	}

 	/*
 	 * @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(Object)
 	 */
 	public Object[] getElements(Object inputElement) {
 		return getChildren(inputElement);
 	}

 	/*
 	 * @see org.eclipse.jface.viewers.IContentProvider#dispose()
 	 */
 	public void dispose() {
 		JavaPlugin.getDefault().getPreferenceStore().removePropertyChangeListener(this);
 	}

 	/**
 	 * Called when the view is closed and opened.
 	 *
 	 * @see org.eclipse.jface.viewers.IContentProvider#inputChanged(Viewer, Object, Object)
 	 */
 	public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
 		fViewer= (TreeViewer)viewer;
 	}

 	/*
 	 * @see org.eclipse.jdt.core.IElementChangedListener#elementChanged(org.eclipse.jdt.core.ElementChangedEvent)
 	 */
 	public void elementChanged(ElementChangedEvent event) {
 		processDelta(event.getDelta());
 	}

 	public void processDelta(IJavaElementDelta delta) {

 		int kind = delta.getKind();
 		final IJavaElement element = delta.getElement();

 		if (element instanceof IPackageFragment) {

 			if (kind == IJavaElementDelta.REMOVED) {

 				postRunnable(new Runnable() {
 					public void run() {
 						Control ctrl = fViewer.getControl();
 						if (ctrl != null && !ctrl.isDisposed()) {
 							if (!fFoldPackages)
 								 fViewer.remove(element);
 							else
 								refreshGrandParent(element);
 						}
 					}
 				});
 				return;

 			} else if (kind == IJavaElementDelta.ADDED) {

 				final Object parent = getParent(element);
 				if (parent != null) {
 					postRunnable(new Runnable() {
 						public void run() {
 							Control ctrl = fViewer.getControl();
 							if (ctrl != null && !ctrl.isDisposed()) {
 								if (!fFoldPackages)
 									 fViewer.add(parent, element);
 								else
 									refreshGrandParent(element);
 							}
 						}
 					});
 				}
 				return;
 			}
 		}
 	}

 	// XXX: needs to be revisited - might be a performance issue
 	private void refreshGrandParent(final IJavaElement element) {
 		if (element instanceof IPackageFragment) {
 			Object gp= getGrandParent((IPackageFragment)element);
 			if (gp instanceof IJavaElement) {
 				IJavaElement el = (IJavaElement) gp;
 				if(el.exists())
 					fViewer.refresh(gp);
 			} else if (gp instanceof IFolder) {
 				IFolder folder= (IFolder)gp;
 				if (folder.exists())
 					fViewer.refresh(folder);
 			}
 		}
 	}

 	private Object getGrandParent(IPackageFragment element) {

 		Object parent= findNextLevelParentByElementName(element);
 		if (parent instanceof IPackageFragmentRoot) {
 			IPackageFragmentRoot root= (IPackageFragmentRoot) parent;
 			if(isRootProject(root))
 				return root.getJavaProject();
 			else return root;
 		}

 		Object grandParent= getParent(parent);
 		if(grandParent==null){
 			return parent;
 		}
 		return grandParent;
 	}

 	private boolean isRootProject(IPackageFragmentRoot root) {
 		if (IPackageFragmentRoot.DEFAULT_PACKAGEROOT_PATH.equals(root.getElementName()))
 			return true;
 		return false;
 	}

 	private void postRunnable(final Runnable r) {
 		Control ctrl= fViewer.getControl();
 		if (ctrl != null && !ctrl.isDisposed()) {

 			Display currentDisplay= Display.getCurrent();
 			if (currentDisplay != null && currentDisplay.equals(ctrl.getDisplay()))
 				ctrl.getDisplay().syncExec(r);
 			else
 				ctrl.getDisplay().asyncExec(r);
 		}
 	}

 	/*
 	 * @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(org.eclipse.jface.util.PropertyChangeEvent)
 	 */
 	public void propertyChange(PropertyChangeEvent event) {
 		if (arePackagesFoldedInHierarchicalLayout() != fFoldPackages){
 			fFoldPackages= arePackagesFoldedInHierarchicalLayout();
 			if (fViewer != null && !fViewer.getControl().isDisposed()) {
 				fViewer.getControl().setRedraw(false);
 				Object[] expandedObjects= fViewer.getExpandedElements();
 				fViewer.refresh();
 				fViewer.setExpandedElements(expandedObjects);
 				fViewer.getControl().setRedraw(true);
 			}
 		}
 	}

 	private boolean arePackagesFoldedInHierarchicalLayout(){
 		return PreferenceConstants.getPreferenceStore().getBoolean(PreferenceConstants.APPEARANCE_FOLD_PACKAGES_IN_PACKAGE_EXPLORER);
 	}
 }
	/*******************************************************************************
	* Copyright (c) 2000, 2006 IBM Corporation and others.
	* 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
	*
	* Contributors:
	* IBM Corporation - initial API and implementation
	*******************************************************************************/
	package org.eclipse.jdt.internal.ui.packageview;

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

	import org.eclipse.core.runtime.CoreException;

	import org.eclipse.core.resources.IFolder;
	import org.eclipse.core.resources.IResource;

	import org.eclipse.swt.widgets.Control;
	import org.eclipse.swt.widgets.Display;

	import org.eclipse.jface.util.IPropertyChangeListener;
	import org.eclipse.jface.util.PropertyChangeEvent;
	import org.eclipse.jface.viewers.TreeViewer;
	import org.eclipse.jface.viewers.Viewer;

	import org.eclipse.jdt.core.ElementChangedEvent;
	import org.eclipse.jdt.core.IJavaElement;
	import org.eclipse.jdt.core.IJavaElementDelta;
	import org.eclipse.jdt.core.IJavaProject;
	import org.eclipse.jdt.core.IPackageFragment;
	import org.eclipse.jdt.core.IPackageFragmentRoot;
	import org.eclipse.jdt.core.JavaCore;
	import org.eclipse.jdt.core.JavaModelException;

	import org.eclipse.jdt.ui.PreferenceConstants;

	import org.eclipse.jdt.internal.ui.JavaPlugin;

	/**
	* Content provider which provides package fragments for hierarchical
	* Package Explorer layout.
	*
	* @since 2.1
	*/
	public class PackageFragmentProvider implements IPropertyChangeListener {

	private TreeViewer fViewer;
	private boolean fFoldPackages;

	public PackageFragmentProvider() {
	fFoldPackages= arePackagesFoldedInHierarchicalLayout();
	JavaPlugin.getDefault().getPreferenceStore().addPropertyChangeListener(this);
	}

	/*
	* @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(Object)
	*/
	public Object[] getChildren(Object parentElement) {
	try {
	if (parentElement instanceof IFolder) {
	IResource[] resources= ((IFolder) parentElement).members();
	return filter(getFolders(resources)).toArray();
	} else if (parentElement instanceof IJavaElement) {
	IJavaElement iJavaElement= (IJavaElement) parentElement;
	int type= iJavaElement.getElementType();

	switch (type) {
	case IJavaElement.JAVA_PROJECT: {
	IJavaProject project= (IJavaProject) iJavaElement;

	IPackageFragmentRoot root= project.findPackageFragmentRoot(project.getPath());
	if (root != null) {
	List children= getTopLevelChildren(root);
	return filter(children).toArray();
	}
	break;
	}
	case IJavaElement.PACKAGE_FRAGMENT_ROOT: {
	IPackageFragmentRoot root= (IPackageFragmentRoot) parentElement;
	if (root.exists()) {
	return filter(getTopLevelChildren(root)).toArray();
	}
	break;
	}
	case IJavaElement.PACKAGE_FRAGMENT: {
	IPackageFragment packageFragment = (IPackageFragment) parentElement;
	if (!packageFragment.isDefaultPackage()) {
	IPackageFragmentRoot root= (IPackageFragmentRoot) packageFragment.getParent();
	List children = getPackageChildren(root, packageFragment);
	return filter(children).toArray();
	}
	break;
	}
	default :
	// do nothing
	}
	}
	} catch (CoreException e) {
	JavaPlugin.log(e);
	}
	return new Object[0];
	}

	private List filter(List children) throws JavaModelException {
	if (fFoldPackages) {
	int size= children.size();
	for (int i = 0; i < size; i++) {
	Object curr= children.get(i);
	if (curr instanceof IPackageFragment) {
	IPackageFragment fragment = (IPackageFragment) curr;
	if (!fragment.isDefaultPackage() && isEmpty(fragment)) {
	IPackageFragment collapsed= getCollapsed(fragment);
	if (collapsed != null) {
	children.set(i, collapsed); // replace with collapsed
	}
	}
	}
	}
	}
	return children;
	}

	private IPackageFragment getCollapsed(IPackageFragment pack) throws JavaModelException {
	IJavaElement[] children= ((IPackageFragmentRoot) pack.getParent()).getChildren();
	IPackageFragment child= getSinglePackageChild(pack, children);
	while (child != null && isEmpty(child)) {
	IPackageFragment collapsed= getSinglePackageChild(child, children);
	if (collapsed == null) {
	return child;
	}
	child= collapsed;
	}
	return child;
	}

	private boolean isEmpty(IPackageFragment fragment) throws JavaModelException {
	return !fragment.containsJavaResources() && fragment.getNonJavaResources().length == 0;
	}

	private static IPackageFragment getSinglePackageChild(IPackageFragment fragment, IJavaElement[] children) {
	String prefix= fragment.getElementName() + '.';
	int prefixLen= prefix.length();
	IPackageFragment found= null;
	for (int i= 0; i < children.length; i++) {
	IJavaElement element= children[i];
	String name= element.getElementName();
	if (name.startsWith(prefix) && name.length() > prefixLen && name.indexOf('.', prefixLen) == -1) {
	if (found == null) {
	found= (IPackageFragment) element;
	} else {
	return null;
	}
	}
	}
	return found;
	}


	private static List getPackageChildren(IPackageFragmentRoot parent, IPackageFragment fragment) throws JavaModelException {
	IJavaElement[] children= parent.getChildren();
	ArrayList list= new ArrayList(children.length);
	String prefix= fragment.getElementName() + '.';
	int prefixLen= prefix.length();
	for (int i= 0; i < children.length; i++) {
	IJavaElement element= children[i];
	if (element instanceof IPackageFragment) { // see bug 134256
	String name= element.getElementName();
	if (name.startsWith(prefix) && name.length() > prefixLen && name.indexOf('.', prefixLen) == -1) {
	list.add(element);
	}
	}
	}
	return list;
	}

	private static List getTopLevelChildren(IPackageFragmentRoot root) throws JavaModelException {
	IJavaElement[] elements= root.getChildren();
	ArrayList topLevelElements= new ArrayList(elements.length);
	for (int i= 0; i < elements.length; i++) {
	IJavaElement iJavaElement= elements[i];
	//if the name of the PackageFragment is the top level package it will contain no "." separators
	if (iJavaElement instanceof IPackageFragment && iJavaElement.getElementName().indexOf('.')==-1) {
	topLevelElements.add(iJavaElement);
	}
	}
	return topLevelElements;
	}

	private List getFolders(IResource[] resources) throws JavaModelException {
	List list= new ArrayList(resources.length);
	for (int i= 0; i < resources.length; i++) {
	IResource resource= resources[i];
	if (resource instanceof IFolder) {
	IFolder folder= (IFolder) resource;
	IJavaElement element= JavaCore.create(folder);
	if (element instanceof IPackageFragment) {
	list.add(element);
	}
	}
	}
	return list;
	}


	/*
	* @see org.eclipse.jface.viewers.ITreeContentProvider#getParent(Object)
	*/
	public Object getParent(Object element) {

	if (element instanceof IPackageFragment) {
	IPackageFragment frag = (IPackageFragment) element;
	//@Changed: a fix, before: if(frag.exists() && isEmpty(frag))

	return filterParent(getActualParent(frag));
	}
	return null;
	}

	private Object getActualParent(IPackageFragment fragment) {
	try {

	if (fragment.exists()) {
	IJavaElement parent = fragment.getParent();

	if ((parent instanceof IPackageFragmentRoot) && parent.exists()) {
	IPackageFragmentRoot root = (IPackageFragmentRoot) parent;
	if (root.isArchive()) {
	return findNextLevelParentByElementName(fragment);
	} else {

	IResource resource = fragment.getUnderlyingResource();
	if ((resource != null) && (resource instanceof IFolder)) {
	IFolder folder = (IFolder) resource;
	IResource res = folder.getParent();

	IJavaElement el = JavaCore.create(res);
	if (el != null) {
	return el;
	} else {
	return res;
	}
	}
	}
	return parent;
	}
	}

	} catch (JavaModelException e) {
	JavaPlugin.log(e);
	}
	return null;
	}

	private Object filterParent(Object parent) {
	if (fFoldPackages && (parent!=null)) {
	try {
	if (parent instanceof IPackageFragment) {
	IPackageFragment fragment = (IPackageFragment) parent;
	if (isEmpty(fragment) && hasSingleChild(fragment)) {
	return filterParent(getActualParent(fragment));
	}
	}
	} catch (JavaModelException e) {
	JavaPlugin.log(e);
	}
	}
	return parent;
	}

	private boolean hasSingleChild(IPackageFragment fragment) {
	return getChildren(fragment).length==1;
	}


	private Object findNextLevelParentByElementName(IPackageFragment child) {
	String name= child.getElementName();

	int index= name.lastIndexOf('.');
	if (index != -1) {
	String realParentName= name.substring(0, index);
	IPackageFragment element= ((IPackageFragmentRoot) child.getParent()).getPackageFragment(realParentName);
	if (element.exists()) {
	return element;
	}
	}
	return child.getParent();
	}


	/*
	* @see org.eclipse.jface.viewers.ITreeContentProvider#hasChildren(Object)
	*/
	public boolean hasChildren(Object element) {

	if (element instanceof IPackageFragment) {
	IPackageFragment fragment= (IPackageFragment) element;
	if(fragment.isDefaultPackage())
	return false;
	}
	return getChildren(element).length > 0;
	}

	/*
	* @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(Object)
	*/
	public Object[] getElements(Object inputElement) {
	return getChildren(inputElement);
	}

	/*
	* @see org.eclipse.jface.viewers.IContentProvider#dispose()
	*/
	public void dispose() {
	JavaPlugin.getDefault().getPreferenceStore().removePropertyChangeListener(this);
	}

	/**
	* Called when the view is closed and opened.
	*
	* @see org.eclipse.jface.viewers.IContentProvider#inputChanged(Viewer, Object, Object)
	*/
	public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
	fViewer= (TreeViewer)viewer;
	}

	/*
	* @see org.eclipse.jdt.core.IElementChangedListener#elementChanged(org.eclipse.jdt.core.ElementChangedEvent)
	*/
	public void elementChanged(ElementChangedEvent event) {
	processDelta(event.getDelta());
	}

	public void processDelta(IJavaElementDelta delta) {

	int kind = delta.getKind();
	final IJavaElement element = delta.getElement();

	if (element instanceof IPackageFragment) {

	if (kind == IJavaElementDelta.REMOVED) {

	postRunnable(new Runnable() {
	public void run() {
	Control ctrl = fViewer.getControl();
	if (ctrl != null && !ctrl.isDisposed()) {
	if (!fFoldPackages)
	fViewer.remove(element);
	else
	refreshGrandParent(element);
	}
	}
	});
	return;

	} else if (kind == IJavaElementDelta.ADDED) {

	final Object parent = getParent(element);
	if (parent != null) {
	postRunnable(new Runnable() {
	public void run() {
	Control ctrl = fViewer.getControl();
	if (ctrl != null && !ctrl.isDisposed()) {
	if (!fFoldPackages)
	fViewer.add(parent, element);
	else
	refreshGrandParent(element);
	}
	}
	});
	}
	return;
	}
	}
	}

	// XXX: needs to be revisited - might be a performance issue
	private void refreshGrandParent(final IJavaElement element) {
	if (element instanceof IPackageFragment) {
	Object gp= getGrandParent((IPackageFragment)element);
	if (gp instanceof IJavaElement) {
	IJavaElement el = (IJavaElement) gp;
	if(el.exists())
	fViewer.refresh(gp);
	} else if (gp instanceof IFolder) {
	IFolder folder= (IFolder)gp;
	if (folder.exists())
	fViewer.refresh(folder);
	}
	}
	}

	private Object getGrandParent(IPackageFragment element) {

	Object parent= findNextLevelParentByElementName(element);
	if (parent instanceof IPackageFragmentRoot) {
	IPackageFragmentRoot root= (IPackageFragmentRoot) parent;
	if(isRootProject(root))
	return root.getJavaProject();
	else return root;
	}

	Object grandParent= getParent(parent);
	if(grandParent==null){
	return parent;
	}
	return grandParent;
	}

	private boolean isRootProject(IPackageFragmentRoot root) {
	if (IPackageFragmentRoot.DEFAULT_PACKAGEROOT_PATH.equals(root.getElementName()))
	return true;
	return false;
	}

	private void postRunnable(final Runnable r) {
	Control ctrl= fViewer.getControl();
	if (ctrl != null && !ctrl.isDisposed()) {

	Display currentDisplay= Display.getCurrent();
	if (currentDisplay != null && currentDisplay.equals(ctrl.getDisplay()))
	ctrl.getDisplay().syncExec(r);
	else
	ctrl.getDisplay().asyncExec(r);
	}
	}

	/*
	* @see org.eclipse.jface.util.IPropertyChangeListener#propertyChange(org.eclipse.jface.util.PropertyChangeEvent)
	*/
	public void propertyChange(PropertyChangeEvent event) {
	if (arePackagesFoldedInHierarchicalLayout() != fFoldPackages){
	fFoldPackages= arePackagesFoldedInHierarchicalLayout();
	if (fViewer != null && !fViewer.getControl().isDisposed()) {
	fViewer.getControl().setRedraw(false);
	Object[] expandedObjects= fViewer.getExpandedElements();
	fViewer.refresh();
	fViewer.setExpandedElements(expandedObjects);
	fViewer.getControl().setRedraw(true);
	}
	}
	}

	private boolean arePackagesFoldedInHierarchicalLayout(){
	return PreferenceConstants.getPreferenceStore().getBoolean(PreferenceConstants.APPEARANCE_FOLD_PACKAGES_IN_PACKAGE_EXPLORER);
	}
	}