public static ActivityEngine getDefaultEngine() {
		if (defaultEngine == null) {
			synchronized (ActivityEngineFactory.class) {
				if (defaultEngine == null) {
					defaultEngine = makeDefaultEngine();
				}				
			}
		}		
		return defaultEngine;
	}
public static ActivityEngine getDefaultEngine ( ) { if ( defaultEngine == null ) { synchronized ( ActivityEngineFactory . class ) { if ( defaultEngine == null ) { defaultEngine = makeDefaultEngine ( ) ; } } } return defaultEngine ; }
Retrieves the currently registered instance of engine, as a default.

@return
the currently registered instance of engine, as a default.