When a method is invoked and it is not part of the derived class, its immediate superclass will be searched; if that class doesn't define the method, its superclass will be searched, and so on.
When a method is invoked and it is not part of the derived class, its immediate superclass will be searched; if that class doesn't define the method, its superclass will be searched, and so on.
当一个方法被调用并且它不属于导出类时，它的直接超类将被搜索；如果那个类也没有定义这个方法，它的超类将被搜索，依此类推。