Bug 32531 NPE importing preferences
Build id: 200302211557 Got error messages when importing preferences. I couldn't reproduce the problem anymore. Will attach stack traces (two generated in a row). Top entries are: java.lang.NullPointerException at org.eclipse.jdt.internal.ui.packageview.PackageExplorerContentProvider.rootsAndC ontainers(PackageExplorerContentProvider.java:153) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerContentProvider.getChildr en(PackageExplorerContentProvider.java:131) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerPart$4.getFilteredChildre n(PackageExplorerPart.java:352) at org.eclipse.jface.viewers.StructuredViewer.getSortedChildren (StructuredViewer.java:555) at org.eclipse.jface.viewers.AbstractTreeViewer.updateChildren (AbstractTreeViewer.java:1282) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh (AbstractTreeViewer.java:925) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh (AbstractTreeViewer.java:934) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh (AbstractTreeViewer.java:895) at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh (AbstractTreeViewer.java:881) at org.eclipse.jface.viewers.StructuredViewer$7.run(StructuredViewer.java:858) at org.eclipse.jface.viewers.StructuredViewer.preservingSelection (StructuredViewer.java:798) at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:856) at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:818) at org.eclipse.jdt.internal.ui.packageview.PackageExplorerPart.propertyChange (PackageExplorerPart.java:1062)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerContentProvider.java
processAffectedChildren(affectedChildren);
	}
	
	protected void processAffectedChildren(IJavaElementDelta[] affectedChildren) throws JavaModelException {
		for (int i= 0; i < affectedChildren.length; i++) {
			processDelta(affectedChildren[i]);
		}
	}
	private boolean isOnClassPath(ICompilationUnit element) throws JavaModelException {
		IJavaProject project= element.getJavaProject();
		if (project == null || !project.exists())
			return false;
		return project.isOnClasspath(element);
	}
	/**
	 * Updates the selection. It finds newly added elements
	 * and selects them.
	 */
	private void updateSelection(IJavaElementDelta delta) {
		final IJavaElement addedElement= findAddedElement(delta);
		if (addedElement != null) {
			final StructuredSelection selection= new StructuredSelection(addedElement);
			postRunnable(new Runnable() {
				public void run() {
					Control ctrl= fViewer.getControl();
					if (ctrl != null && !ctrl.isDisposed()) {
						
						
						if (fViewer.testFindItem(addedElement) != null)
							fViewer.setSelection(selection);