The JavaTM Tutorial

| Start of Tutorial > Start of Trail > Start of Lesson | Search Feedback Form

Trail: Learning the Java Language
Lesson: Classes and Inheritance

## Answers to Questions and Exercises: Creating Classes

> ### Questions

> > Question 1: Consider the following class:

> > >     public class IdentifyMyParts {
> > >         public static int x = 7;
> > >         public int y = 3;
> > >     }

> > > a. How many class variables does the IdentifyMyParts class contain? What are their names?
> > > Answer 1a: 1, x

> > > b. How many instance variables does the IdentifyMyParts class contain? What are their names?
> > > Answer 1b: 1, y

> > > c. What is the output from the following code:

> > > >     IdentifyMyParts a = new IdentifyMyParts();
> > > >     IdentifyMyParts b = new IdentifyMyParts();
> > > >     a.y = 5;
> > > >     b.y = 6;
> > > >     a.x = 1;
> > > >     b.x = 2;
> > > >     System.out.println("a.y = " + a.y);
> > > >     System.out.println("b.y = " + b.y);
> > > >     System.out.println("a.x = " + a.x);
> > > >     System.out.println("b.x = " + b.x);

> > > Answer 1c: Here is the output:

> > > >      a.y = 5
> > > >      b.y = 6
> > > >      a.x = 2
> > > >      b.x = 2

> > ### Exercises

> > > Exercise 1: Write a class whose instances represent a playing card from a deck of cards.
> > > Answer 1: Card.java

> > > Exercise 2: Write a class whose instances represents a deck of cards.
> > > Answer 2: See Deck.java .

> > > Exercise 3: Write a small program to test your deck and card classes. The program can be as simple as creating a deck of cards and displaying its cards.
> > > Answer 3: See DisplayDeck.java .

| Start of Tutorial > Start of Trail > Start of Lesson | Search Feedback Form

Copyright 1995-2004 Sun Microsystems, Inc. All rights reserved.