Trail: Learning the Java Language
Lesson: Classes and Objects
Answers to Questions and Exercises: Nested Classes

Questions

Question 1: The program Problem.java doesn't compile. What do you need to do to make it compile? Why?
Answer 1: Delete static in front of the declaration of the Inner class. An static inner class does not have access to the instance fields of the outer class. See ProblemSolved.java.


Question 2: Use the Java API documentation for the Box class (in the javax.swing package) to help you answer the following questions.

a. What static nested class does Box define?
Answer 2a: Box.Filler

b. What inner class does Box define?
Answer 2b: Box.AccessibleBox

c. What is the superclass of Box’s inner class?
Answer 2c:[java.awt.]Container.AccessibleAWTContainer

d. Which of Box’s nested classes can you use from any class?
Answer 2d: Box.Filler

e. How do you create an instance of Box’s Filler class?
Answer 2e: new Box.Filler(minDimension, prefDimension, maxDimension)

Exercises

Exercise 1: Get the file Class1.java.
a. Compile and run Class1. What is the output?
Answer:
InnerClass1: getString invoked.
InnerClass1: getAnotherString invoked.
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