"Java" multi-state after-school action Brain

1.

1. What is the result of the program running on the left?

2. How do you explain that you will get such output?

3. The computer is not wrong, the reason why you get such a running result is also a reason, then from these running results, you can summarize the Java syntax features?

When a subclass has the same method as the parent class, and a parent class variable refers to a subclass object, which method is called, determined by the object's own "true" type, that is, the object is a subtype, it calls the method of the subtype, it is the parent type, and it invokes the method of the parent type. This feature is actually a concrete representation of the object-oriented "polymorphic" feature.

If the child class has the same field as the parent class, the fields in the subclass are substituted or hidden from the fields of the parent class, and the fields in the subclass are accessed (not the fields in the parent class). If the subclass method does want to access a field that is hidden in the parent class with the same name, it can be accessed with the Super keyword. If the subclass is used as a parent class, the field accessed through the subclass is the parent class!

2. Use polymorphic method to simulate ATM operation flow.

Results:

"Java" multi-state after-school action Brain