ObjectUtil { public static boolean isNull(Object obj) { return obj == null; }  static boolean isNull(Object obj); static boolean isNotNull(Object obj); static boolean andIsNull(Object... objects); static boolean orIsNull(Object... objects); static boolean equals(Object obj1, Object obj2); static boolean same(Object obj1, Object obj2);  }
@Test public void testIsNull() { assertTrue(ObjectUtil.isNull(null)); assertFalse(ObjectUtil.isNull("")); }