Java 2 For Dummies

by Barry Burd

Please note: This page applies almost exclusively to the first edition of Java 2 For Dummies. If you have the second edition visit this page instead.

 Errata: 

Which printing do you have?

In the book's first few pages, look for a page with all kinds of official-looking stuff (the publisher's address, the Library of Congress Control Number, the ISBN, and so on). On that page, look for a line with descending numbers on it.

10 9 8 7 6 5 4 3 2

The smallest number is the number of your printing. For instance, the line shown above is in books made during the 2^nd printing.

There are several things you can do about this:

• You can visit http://www.java.com/en/download/windows_automatic.jsp to download a newer Java Plug-in for your Web browser. (This may or may not help.)
• You can skip the examples in Chapter 2 pertaining to applets. The fact is, applets aren't nearly as important to Java developers as they used to be. Most people use Java for non-applet processing these days, so my book doesn't return to the subject of applets until much later on (in one of the Bonus chapters on the CD-ROM). So, unless you have some special reason for needed to know about applets, you can just skip this part of Chapter 2, and move on.
• You can run the applet with Sun's appletviewer. To do this, go to the command prompt, and type

  
  appletviewer MortgageApplet.html
  
  

• I've checked the Java 1.4-compiled version of MortgageApplet in Netscape Navigator 6, and it seems to load and run there.
• You can download this version of MortgageApplet.class that I compiled under Java 1.3.
• (Not recommended): You can visit Sun's Web site, download a copy of the older Java 1.3 SDK, and revert to this older version of Java.

MortgageText.java
MortgageWindow.java
MortgageApplet.java

Thanks to Jeff Goldstein

For instance, the end of the first full paragraph of that section should read as follows:
"The increment operators use double plus signs (++), and the decrement operator uses double minus signs (--). To see how they work ..."

public class MakeChange
{
   public static void main(String args[])
   {
      int quarters, dimes, nickels, cents;
      int whatsLeft, total;

      total = 248;
      quarters = total/25;
      whatsLeft = total%25;

      dimes = whatsLeft/10;
      whatsLeft = whatsLeft%10;

      nickels = whatsLeft/5;
      whatsLeft = whatsLeft%5;

      cents = whatsLeft;

      System.out.println("From " + total + " cents get");
      System.out.println(quarters + " quarters");
      System.out.println(dimes + " dimes");
      System.out.println(nickels + " nickels");
      System.out.println(cents + " cents");
   }

}

Thanks to David Wurster

public class UseAssignmentOperators
{
   public static void main(String args[])
   {
      int numberOfBunnies;
      int numberExtra;
      numberOfBunnies=27;
      numberExtra=53;

      numberOfBunnies += 1;
      System.out.println(numberOfBunnies);

      numberOfBunnies += 5;
      System.out.println(numberOfBunnies);

      numberOfBunnies *= 2;
      System.out.println(numberOfBunnies);

      numberOfBunnies += numberExtra;
      System.out.println(numberOfBunnies);

      System.out.println(numberOfBunnies -= 7);

      System.out.println(numberOfBunnies = 100);
   }
}

Thanks to Bo Isaksson

import java.text.NumberFormat;

public class InventoryD
{
   public static void main(String args[])
   {
      String numBoxesIn;
      int numBoxes;
      double boxPrice = 3.25;
      NumberFormat currency =
         NumberFormat.getCurrencyInstance();

      System.out.print("How many boxes do we have? ");
      numBoxesIn = DummiesIO.getString();

      try
      {
         if (numBoxesIn.equals(""))
            throw new NoInputException();

         numBoxes = Integer.parseInt(numBoxesIn);
         if (numBoxes < 0)
            throw new NegativeNumberException();

         System.out.print("The value is ");
         System.out.println
            (currency.format(numBoxes*boxPrice));
      }

      catch (NegativeNumberException e)
      {
         System.out.print(numBoxesIn);
         System.out.println("? That's impossible!");
      }

      catch (NumberFormatException e)
      {
         System.out.println("That's not a number.");
      }

      catch (Exception e)
      {
         System.out.print("Something went wrong, ");
         System.out.print("but I'm clueless about what ");
         System.out.println("it actually was.");
      }
      System.out.println("That's that.");
   }
}


class NegativeNumberException extends Exception
{
}


class NoInputException extends NumberFormatException
{
}

Thanks to Tom Cavaiani

The most recent version of the MRJ implements an older version of Java - Java 1.1.8. So some of the code in Java 2 For Dummies won't work under the MRJ. I've created a revised version of DummiesIO.java that works with the MRJ. When you compile it, you'll get a deprecation warning, but the warning doesn't stop you from running the code.

Also, please note: To be able to read from the keyboard (as in MortgageText.java, from Chapter 2), you have to tweak the MRJ settings. There's a picture illustrating what you have to do at http://rescomp.stanford.edu/~ejalbert/faqs/stdin.html.

Thanks to Andrew Beckman and John Muccigrosso

Visit the book's page at Hungry Minds.

If you have any comments or questions for Barry Burd, please send email to j2fd at BurdBrain.com. Thank you.