Bug 18132 New wizards should verify if folder is on classpath
1. create J project 'P' with source folder setup (source folder 'src') 2. use new wizard to create a class ==> you can create a class inside 'P' or in a folder which is not on the classpath
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/wizards/NewContainerWizardPage.java
import org.eclipse.jdt.core.JavaCore;
import org.eclipse.jdt.core.JavaModelException;
import org.eclipse.jdt.ui.JavaElementContentProvider;
import org.eclipse.jdt.ui.JavaElementLabelProvider;
import org.eclipse.jdt.ui.JavaElementSorter;
import org.eclipse.jdt.internal.corext.util.JavaModelUtil;
import org.eclipse.jdt.internal.ui.JavaPlugin;
import org.eclipse.jdt.internal.ui.dialogs.StatusInfo;
import org.eclipse.jdt.internal.ui.javaeditor.EditorUtility;
import org.eclipse.jdt.internal.ui.wizards.NewWizardMessages;
import org.eclipse.jdt.internal.ui.wizards.TypedElementSelectionValidator;
import org.eclipse.jdt.internal.ui.wizards.TypedViewerFilter;
import org.eclipse.jdt.internal.ui.wizards.dialogfields.DialogField;
import org.eclipse.jdt.internal.ui.wizards.dialogfields.IDialogFieldListener;
import org.eclipse.jdt.internal.ui.wizards.dialogfields.IStringButtonAdapter;
import org.eclipse.jdt.internal.ui.wizards.dialogfields.LayoutUtil;
import org.eclipse.jdt.internal.ui.wizards.dialogfields.StringButtonDialogField;
/**
 * Base class for Java wizards. Provides source folder selection UI, validation and creation.
 * @since 2.0
 */
public abstract class NewContainerWizardPage extends NewElementWizardPage {
	
	/**
	 * container field id
	 */
	protected static final String CONTAINER= "NewContainerWizardPage.container"; 
	/**
	 * Status of last validation
	 */