Java-preliminary Understanding-Common object API (set frame-generics-generic-limit-lower)

One.

Then the previous section of the example to expand the description, the first question mark in the form of writing the whole is the following. What type is a subclass of object.

In the example in the previous section, the person is fixed and its subclasses can be arbitrarily changed, but the upper bound is fixed.

For the lower bound for example, demonstrate that the iterator generics and get iterator generic collections are consistent. Iterators are taken over, and what is passed is, of course, what gets.

How does it pass? It is OK to pass student and person in the collection of the main function, the worker is not. But its application is not very obvious. This is not a lot of practice, so when to do it? Next, the upper and lower limits are reflected in the set.

Java-preliminary Understanding-Common object API (set frame-generics-generic-limit-lower)