Mastering Java: The Ultimate Quiz for 'Thinking in Java'

What does the class NullRobot demonstrate?

1. The use of null objects to avoid checking for null

2. The use of dynamic proxy to simulate null behavior in objects

3. How to implement a singleton pattern with null objects

4. The practice of using static factory methods for object creation

The correct answer is: The use of dynamic proxy to simulate null behavior in objects

Explanation The NullRobot class demonstrates the use of dynamic proxy to simulate null behavior in objects. This means that instead of having to explicitly check for null values in our code, we can use the NullRobot class to handle those cases for us. The other options are incorrect because they do not pertain to the use of dynamic proxy or null behavior. Option A mentions null objects, but does not mention the use of dynamic proxy. Option C mentions a singleton pattern, which is unrelated to the use of dynamic proxy. Option D mentions static factory methods, which also do not relate to the use of dynamic proxy.