Bug 55399 exception on Code Style preference page
Nightly build 0319 - start a new eclipse install - show the Java > Code Style preference page - will get the attached exception
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/NameConventionConfigurationBlock.java
private void packEntries() {
		for (int i= 0; i < fNameConventionList.getSize(); i++) {
			NameConventionEntry entry= (NameConventionEntry) fNameConventionList.getElement(i);
			fWorkingValues.put(entry.suffixkey, entry.suffix);
			fWorkingValues.put(entry.prefixkey, entry.prefix);
		}
	}
		
	private void doEditButtonPressed() {
		NameConventionEntry entry= (NameConventionEntry) fNameConventionList.getSelectedElements().get(0);
		String title;
		String message;
		switch (entry.kind) {
			case FIELD:
				title= PreferencesMessages.getString("NameConventionConfigurationBlock.field.dialog.title"); 
				message= PreferencesMessages.getString("NameConventionConfigurationBlock.field.dialog.message"); 
				break;
			case STATIC:
				title= PreferencesMessages.getString("NameConventionConfigurationBlock.static.dialog.title"); 
				message= PreferencesMessages.getString("NameConventionConfigurationBlock.static.dialog.message"); 
				break;
			case ARGUMENT:
				title= PreferencesMessages.getString("NameConventionConfigurationBlock.arg.dialog.title"); 
				message= PreferencesMessages.getString("NameConventionConfigurationBlock.arg.dialog.message"); 
				break;
			default:
				title= PreferencesMessages.getString("NameConventionConfigurationBlock.local.dialog.title"); 
				message= PreferencesMessages.getString("NameConventionConfigurationBlock.local.dialog.message"); 
		}