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

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xii More free books @ www.BingEbook.com Beginning Programming with Java For Dummies, 2nd Edition Building a Nest..............................................................................................170 Nested if statements ..........................................................................171 Cascading if statements.....................................................................172 Enumerating the Possibilities.....................................................................175 Creating an enum type.......................................................................176 Using an enum type............................................................................176 Creating a project with two Java source files .................................179 Chapter 11: How to Flick a Virtual Switch . . . . . . . . . . . . . . . . . . . . . .181 Meet the switch Statement .........................................................................181 The cases in a switch statement ......................................................183 The default in a switch statement....................................................184 Picky details about the switch statement .......................................185 To break or not to break....................................................................188 Using Fall-through to Your Advantage.......................................................190 Using a Conditional Operator.....................................................................192 Chapter 12: Around and Around It Goes . . . . . . . . . . . . . . . . . . . . . . . .195 Repeating Instructions Over and Over Again (Java while Statements)...........................................................................196 Following the action in a loop...........................................................197 No early bailout ..................................................................................199 Thinking about Loops (What Statements Go Where)..............................200 Finding some pieces...........................................................................200 Assembling the pieces .......................................................................203 Getting values for variables ..............................................................203 From infinity to affinity ......................................................................205 Thinking About Loops (Priming) ...............................................................207 Working on the problem....................................................................209 Fixing the problem .............................................................................212 Chapter 13: Piles of Files: Dealing with Information Overload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215 Running a Disk-Oriented Program .............................................................216 A sample program ..............................................................................217 Creating code that messes with your hard drive...........................219 Running the sample program ...........................................................222 Troubleshooting problems with disk files ......................................224 Writing a Disk-Oriented Program ...............................................................226 Reading from a file..............................................................................227 Writing to a file....................................................................................227 Writing, Rewriting, and Re-rewriting..........................................................230 Chapter 14: Creating Loops within Loops . . . . . . . . . . . . . . . . . . . . . . .233 Paying Your Old Code a Little Visit............................................................234 Reworking some existing code .........................................................235 Running your code .............................................................................236
More free books @ www.BingEbook.com Table of Contents Creating Useful Code ...................................................................................236 Checking for the end of a file ............................................................237 How it feels to be a computer...........................................................239 Why the computer accidentally pushes past the end of the file ...................................................................241 Solving the problem ...........................................................................243 Chapter 15: The Old Runaround . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .245 Repeating Statements a Certain Number Times (Java for Statements)...............................................................................246 The anatomy of a for statement .......................................................248 Initializing a for loop ..........................................................................250 Using Nested for Loops ...............................................................................252 Repeating Until You Get What You Need (Java do Statements).............254 Getting a trustworthy response .......................................................255 Deleting files........................................................................................257 Using Java’s do statement.................................................................258 A closer look at the do statement ....................................................259 Repeating with Predetermined Values (Java’s Enhanced for Statement)............................................................260 Creating an enhanced for loop .........................................................261 Nesting the enhanced for loops .......................................................263 Part IV: Using Program Units.....................................269 Chapter 16: Using Loops and Arrays . . . . . . . . . . . . . . . . . . . . . . . . . . .271 Some for Loops in Action............................................................................271 Deciding on a loop’s limit at runtime...............................................274 Using all kinds of conditions in a for loop.......................................275 Reader, Meet Arrays; Arrays, Meet the Reader ........................................277 Storing values in an array..................................................................280 Creating a report ................................................................................282 Working with Arrays ....................................................................................283 Chapter 17: Programming with Objects and Classes . . . . . . . . . . . . .289 Creating a Class ............................................................................................290 Reference types and Java classes ....................................................291 Using a newly defined class ..............................................................291 Running code that straddles two separate files.............................293 Why bother?........................................................................................294 From Classes Come Objects .......................................................................294 Understanding (or ignoring) the subtleties ....................................297 Making reference to an object’s parts .............................................297 Creating several objects ....................................................................298 Another Way to Think About Classes........................................................300 Classes, objects, and tables ..............................................................301 Some questions and answers ...........................................................302 xiii
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Page 5 and 6: About the Author More free books @
Page 7 and 8: Dedication More free books @ www.Bi
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Chapter 4 Exploring the Parts of a
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you should avoid naming it Canada,
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Figure 4-3: A pair of curly braces
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Figure 4-5: The terminology describ
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Figure 4-6: Calling the System.out.
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In This Chapter Chapter 5 Composing
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Figure 5-1: What part of the word
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1. Launch JCreator. 2. From JCreato
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Figure 5-6: The computer substitute
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Also, the table’s story has a sur
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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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