BarcodeGeneratorProvider { public static synchronized BarcodeGeneratorProvider getInstance() { if (instance == null) { instance = new BarcodeGeneratorProvider(); LOGGER.log(Level.INFO, "Created new instance."); } return instance; } private  BarcodeGeneratorProvider(); static synchronized BarcodeGeneratorProvider getInstance(); Collection<String> getAvailableBarcodeGenerators(); BarcodeGenerator getBarcodeGenerator(String id);  }
@Test public void getInstance() { System.out.println("getInstance"); BarcodeGeneratorProvider result = BarcodeGeneratorProvider.getInstance(); assertNotNull(result); BarcodeGeneratorProvider result2 = BarcodeGeneratorProvider.getInstance(); assertEquals(result, result2); }