### Question:
PropertyUtils { public static String getString(String key, String defaultVal) { String val = properties.getProperty(key.trim()); return val == null ? defaultVal : val; } private  PropertyUtils(); static String getString(String key, String defaultVal); static String getString(String key); static int getInt(String key); static int getInt(String key, int defaultValue); static boolean getBoolean(String key); static Boolean getBoolean(String key, boolean defaultValue); static long getLong(String key, long defaultVal); static long getLong(String key); static double getDouble(String key, double defaultVal); T getEnum(String key, Class<T> type,
                                         T defaultValue);  }### Answer:
@Test public void testGetString() { String result = PropertyUtils.getString("test.string"); logger.info(result); assertEquals("teststring", result); result = PropertyUtils.getString(null); assertNull(result); }