LabelContainer { synchronized public static LabelContainer getInstance() { if (instance == null) { instance = new LabelContainer(); } return instance; } protected  LabelContainer(); synchronized static LabelContainer getInstance(); synchronized void addLabel(String label); synchronized Integer getLabelID(String label); synchronized String getLabel(Integer labelID); synchronized int getSize();  }
@Test public void testGetInstance() { Assert.assertNotNull(LabelContainer.getInstance()); }