Q15: Classes and Objects

• Take out a piece of paper and put your name on the upper right corner.

• Answer the following questions:

  1. Object-oriented programming uses classes and objects. What are classes and what are objects? What is the relationship between classes and objects?

  2. What are instance variables and instance methods?

  3. Explain what null means in Java, and why this special value is necessary.

Finish your answers before the timer runs out.