Part II: Writing Your Own Java Programs - Get a Free Blog

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24 Part I: Revving Up Downloading and Installing the Software You Need If you’ve paid for this book, and you already have a working computer, you’ve already spent all the money you need to spend. All the software you need for learning Java is free for the downloading. Downloading and installing a Java compiler When I want the weather to be sunny, I bring an umbrella to work. Bringing an umbrella tells the weather gods to do the opposite of whatever Barry anticipates. The same kind of thing happens with the Java Web site. If I want someone to redesign the Web site, I just write an article describing exactly how to navigate the site. Sometime between the time of my writing and the date of the article’s publication, the people at Sun Microsystems reorganize the entire Web site. It’s as dependable as the tides. Anyway, the Java Web site is in a constant state of flux. That’s why I don’t put detailed instructions for navigating the Java Web site in this book. Instead, I offer some timeless tips. If this section’s “timeless tips” aren’t specific enough for you, visit this book’s Web site at http://www.dummies.com/go/bpjavafd. At the Web site, you can find up-to-date instructions on getting the software you need. What number comes after 1.4.2_06? The numbering of Java’s versions is really confusing. First comes Java 1.0, then Java 1.1, then Java 2 Standard Edition 1.2 (J2SE 1.2). Yes, the “Java 2” numbering overlaps partially with the “1.x” numbering. Next come versions 1.3 and 1.4. After version 1.4.1 comes version 1.4.2 (with intermediate stops at versions like 1.4.1_02). After 1.4.2_06, the next version is version 5.0. (That’s no misprint. Version 5.0 comes immediately after the 1.4 versions, although More free books @ www.BingEbook.com some people use the term “Java 1.5” when they mean “Java 5.0.”) The formal name for version 5.0 is “Java 2 Platform, Standard Edition 5.0.” And to make matters even worse, the people at Sun Microsystems are thinking about removing the extra “2.” So after “Java 2, 5.1” you may see plain old “Java, 5.2.” That’s what happens when a company lets marketing people call the shots.
More free books @ www.BingEbook.com With all these disclaimers in mind, you can get a Java compiler by following these steps: 1. Visit java.sun.com/j2se. Chapter 2: Setting Up Your Computer 2. Look for a Download J2SE link (or something like that). The page may have several J2SE version numbers for you to choose from. You may see links to J2SE 1.4.2, J2SE 5.0, and beyond. If you’re not sure which version you want, choosing the highest version number is probably safe, even if that version number is labeled “Beta.” (The Java beta releases are fairly sturdy.) While you wander around, you may notice links labeled J2EE or J2ME. If you know what these are, and you know you need them, then by all means, download these goodies. But if you’re not sure, then bypass both the J2EE and the J2ME. Instead, follow the J2SE (Java 2 Standard Edition) links. The abbreviation J2EE stands for Java 2 Enterprise Edition and J2ME stands for Java 2 Micro Edition. You don’t need the J2EE or the J2ME to run any of the examples in this book. 3. On the J2SE download page, look for an appropriate download link. A download link is “appropriate” as long as the link refers to J2SE (Java 2 Platform, Standard Edition), to JDK (Java Development Kit), and to your particular operating system (such as Windows, Linux, or Solaris). From all possible links, you may have to choose between links labeled for 32bit systems and links labeled for 64-bit systems. If you don’t know which to choose, and you’re running Windows, then you probably have a 32-bit system. The Sun Microsystems download page offers you a choice between the JDK (Java Development Kit) and the JRE (Java Runtime Environment). The JDK download contains more than the JRE download, and you need more than that feeble JRE download. You need to download the entire JDK. Sun’s regular J2SE page has links for Windows, Linux, and Solaris users. If your favorite operating system isn’t Windows, Linux, or Solaris, don’t despair. You can probably find an appropriate Java compiler by searching on the Web. If you use Macintosh OS X, go straight to developer.apple. com/java. Java 5.0 comes with OS 10.4. Another choice you may have to make is between an offline and online installation: • With the offline installation, you begin by downloading a 50MB setup file. The file takes up space on your hard drive, but if you ever need to install the JDK again, you have the file on your own computer. Until you update your version of the JDK, you don’t need to download the JDK again. 25
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Page 5 and 6: About the Author More free books @
Page 7 and 8: Dedication More free books @ www.Bi
Page 21 and 22: If you already know what computer p
Page 27 and 28: In This Chapter What computer prog
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Page 33 and 34: What is bytecode, anyway? Look at L
Page 35 and 36: Figure 1-5: Two ways to run a compu
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Page 45 and 46: Figure 2-1: The docs subdirectory o
Page 47 and 48: 5. From My Computer navigate to wha
Page 49 and 50: Figure 2-4: JCreator’s work area.
Page 51 and 52: In This Chapter Compiling and runn
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Page 55 and 56: Figure 3-4: The compiling process i
Page 57 and 58: The version of JCreator that you do
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Page 71 and 72: you should avoid naming it Canada,
Page 73 and 74: Figure 4-3: A pair of curly braces
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At first you may think this guy has
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Figure 5-8: A helpful error message
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Chapter 5: Composing a Program The
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Avoid the knee-jerk response. Some
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Chapter 5: Composing a Program One
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Figure 5-13: Whadaya mean “NoSuch
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Spaces and indentation Java isn’t
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Chapter 6 Using the Building Blocks
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Figure 6-2: A variable (before and
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Figure 6-4: Reading an assignment s
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Figure 6-6: An extreme close-up of
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Figure 6-7: Getting the value of a
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Methods and assignments Note how I
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You can’t drag statements outside
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In This Chapter Processing whole n
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eflected nicely in Java. In Listing
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Figure 7-4: How to make six kids ve
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Figure 7-5: Hey, bud! Got change fo
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Figure 7-7: Using preincrement. Mor
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To cram a double value into an int
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Look at the bold line of code in Fi
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Are you trying to decide between us
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Figure 7-13: Storing the digits 422
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Chapter 8 Numbers? Who Needs Number
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Figure 8-2: The action in Listing 8
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Figure 8-5: Stop those pots! The co
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I wish I could give you twelve simp
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To represent a lone character in th
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Figure 8-11: The Fahrenheit tempera
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Figure 8-13: The Fahrenheit variabl
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In This Chapter Chapter 9 Forks in
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Figure 9-3: An if statement and its
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Figure 9-4: The allknowing Java pro
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Randomness makes me dizzy When you
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Anyway, whether you’re skinning c
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Anyway, notice that the value of ra
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An elegant way to think about if st
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In This Chapter Chapter 10 Which Wa
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Figure 10-2: Admission prices for B
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Figure 10-4: The choices in Listing
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Figure 10-6: Running the code in Li
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Figure 10-8: A capital offense. Fig
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} } More free books @ www.BingEbook
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Listing 10-8: Proud Winners and Sor
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Chapter 11 How to Flick a Virtual S
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Figure 11-2: A fork with eleven pro
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Figure 11-4: How many days until th
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Figure 11-6: From your mind to the
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In This Chapter Chapter 12 Around a
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Figure 12-1: Momma needs a new pair
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Figure 12-4: Look! I rolled a seven
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Figure 12-5: You win sum; you lose
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Figure 12-8: An incorrect run. You
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If you’ve read this whole section
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Figure 12-11: Jumping into a loop.
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Figure 12-13: The strategy in Listi
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In This Chapter Chapter 13 Piles of
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218 Part III: Controlling the Flow
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Figure 15-5: A readable display of
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Figure 15-6: No! Don’t do it! Mor
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Figure 15-7: Here we go loop, do lo
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That’s why my writing a Java prog
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In general, a someEnumTypeName.valu
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Figure 15-10: Entering loops for th
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Figure 15-14: Traveling a second ti
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In This Chapter Using for loops to
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Listing 16-1 uses a for loop — a
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Figure 16-3: A few one-room reports
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Listing 16-3 has a big fat conditio
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guestsIn[6] = 0; On one weekday, bu
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In This Chapter Creating classes C
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Figure 17-2: The code in Listing 17
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The two programs (in Listings 17-1
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Listing 17-4: What It Means to Be a
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Figure 17-6: From one class come th
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Figure 17-7: A table of purchases.
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Chapter 18 Using Methods and Variab
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Putting String variables to good us
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To display a String value, you can
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Figure 18-4: This looks even worse.
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Figure 18-6: Viewing the String cla
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Combining and using data At this po
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Turning strings into numbers The co
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Figure 18-9: Do you have change for
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Packages and import declarations In
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That’s very nice! How about the S
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class Check { int number; double am
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Chapter 19 Creating New Java Method
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The last names in Figure 19-1 may s
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Figure 19-2: Two objects, each with
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Chapter 19: Creating New Java Metho
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} void fillWithData() { Random myRa
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} void display() { NumberFormat cur
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Figure 19-6: Passing a value to a m
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Figure 19-7: Cbj’s account and Br
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In This Chapter Swinging into acti
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Figure 20-1: What a nice window! Mo
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Figure 20-4: The frame in Listing 2
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Taking Action The previous section
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Figure 20-6: A brandnew frame. Figu
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In This Chapter Chapter 21 Ten Sets
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Chapter 22 Ten Useful Classes in th
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Math Do you have any numbers to cru
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• Symbols • && (and operator),
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• C • Calling addInterest Metho
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File➪Open Workspace (JCreator), 3
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errors, diagnosing errors. See also
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input file creating, 222-223 naming
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enum type, 176 Faulty Password Chec
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pack, 352 parentheses and, 328 pars
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method and, 328 parameters and, 336
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testing code, 222-224 troubleshooti
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static, 320-323 String class, 305-3
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