Answers to Questions

1. Real-world objects contain state and behavior.

2. A software object's state is stored in fields.

3. A software object's behavior is exposed through methods.

4. Hiding internal data from the outside world, and accessing it only through publicly exposed methods is known as data encapsulation.

5. A blueprint for a software object is called a class.

6. Common behavior can be defined in a superclass and inherited into a subclass using the extends keyword.

7. A collection of methods with no implementation is called an interface.

8. A namespace that organizes classes and interfaces by functionality is called a package.

9. The term API stands for Application Programming Interface.

Answers to Exercises

1. Your answers will vary depending on the real-world objects that you are modeling.

2. Your answers will vary here as well, but the error message will specifically list the required methods that have not been implemented.