Java Programming for Android Developers For Dummies

Barry Burd, PhD, is a professor in the Department of Mathematics and Computer Science at Drew University in Madison, New Jersey. He has lectured at conferences in the United States, Europe, Australia, and Asia. He hosts podcasts and videos about software and other technology topics. He is the author of many articles and books, including Java For Dummies.

• Introduction 1How to Use This Book 1Conventions Used in This Book 2What You Don’t Have to Read 2Foolish Assumptions 3How This Book Is Organized 4Part 1: Getting Started with Java Programming for Android Developers 4Part 2: Writing Your Own Java Programs 5Part 3: Working with the Big Picture: Object-Oriented Programming 5Part 4: Powering Android with Java Code 5Part 5: The Part of Tens 5More on the web! 6Icons Used in This Book 6Beyond the Book 7Where to Go from Here 7Part 1: Getting Started with Java Programming For Android Developers 9Chapter 1: All about Java and Android 11The Consumer Perspective 12The Many Faces of Android 13The Developer Perspective 15Java 15Xml 18Linux 19From Development to Execution with Java 20What is a compiler? 20What is a virtual machine? 24Java, Android, and Horticulture 26Chapter 2: Getting the Tools That You Need 27The Stuff You Need 28If You Don’t Like to Read the Instructions . 29Getting This Book’s Sample Programs 32Setting Up Java 33Setting Up Android Studio and the Android SDK 37Launching the Android Studio IDE 38Opening One of This Book’s Sample Programs 40Using Android Studio 42Starting up 42The main window 43Things You Might Eventually Have to Do 48Installing new versions (and older versions) of Android 49Creating an Android virtual device 50Chapter 3: Creating and Running an Android App 55Creating Your First App 56First things first 57Launching your first app 61If the Emulator Doesn’t Behave 63Running third-party emulators 64Testing apps on a physical device 65The Project Tool Window 68The app/manifests branch 68The app/java branch 69The app/res branches 69The Gradle scripts branch 70Dragging, Dropping, and Otherwise Tweaking an App 70Creating the “look” 71Coding the behavior 83What All That Java Code Does 88Finding the EditText and TextView components 88Responding to a button click 90The rest of the code 91Going Pro 93Part 2: Writing Your Own Java Programs 95Chapter 4: An Ode to Code 97Hello, Android! 97The Java Class 99The names of classes 103Why Java Methods Are Like Meals at a Restaurant 105What does Mom’s Restaurant have to do with Java? 106Method declaration 106Method call 108Method parameters 108The chicken or the egg 109How many parameters? 109Method declarations and method calls in an Android program 111Punctuating Your Code 116Comments are your friends 119What’s Barry’s excuse? 122All About Android Activities 123Extending a class 124Overriding methods 124An activity’s workhorse methods 125Chapter 5: Java’s Building Blocks 129Info Is As Info Does 130Variable names 133Type names 133Assignments and initializations 134Expressions and literals 136How to string characters together 139Java’s primitive types 140Things You Can Do with Types 142Add letters to numbers (Huh?) 144Java’s exotic assignment operators 146True bit 147Java isn’t like a game of horseshoes 148Use Java’s logical operators 150Parenthetically speaking 155Chapter 6: Working with Java Types 157Working with Strings 157Going from primitive types to strings 158Going from strings to primitive types 159Getting input from the user 160Practice Safe Typing 163Widening is good; narrowing is bad 165Incompatible types 166Using a hammer to bang a peg into a hole 167Chapter 7: Though These Be Methods, Yet There Is Madness in’t 169Minding Your Types When You Call a Method 170Method parameters and Java types 173If at first you don’t succeed 174Return types 174The great void 175Displaying numbers 176Primitive Types and Pass-by Value 177What’s a developer to do? 181A final word 183Chapter 8: What Java Does (and When) 187Making Decisions 187Java if statements 189Choosing among many alternatives 191Some formalities concerning Java switch statements 198Repeating Instructions Over and Over Again 199Check, and then repeat 200Repeat, and then check 207Count, count, count 211What’s Next? 214Part 3: Working with the Big Picture: Object-oriented Programming 215Chapter 9: Why Object-Oriented Programming Is Like Selling Cheese 217Classes and Objects 219What is a class, really? 220What is an object? 222Creating objects 223Reusing names 227Calling a constructor 230More About Classes and Objects (Adding Methods to the Mix) 232Constructors with parameters 235The default constructor 239This is it! 240Giving an object more responsibility 242Members of a class 245Reference types 246Pass by reference 247Java’s Modifiers 251Public classes and default-access classes 251Access for fields and methods 253Using getters and setters 257What does static mean? 260To dot, or not 263A bad example 264What’s Next? 265Chapter 10: Saving Time and Money: Reusing Existing Code 267The Last Word on Employees — Or Is It? 268Extending a class 269Overriding methods 272Java’s super keyword 278Java annotations 279More about Java’s Modifiers 281Keeping Things Simple 285Using an interface 286Some Observations about Android’s Classes 291Java’s super keyword, revisited 292Casting, again 293Part 4: Powering Android with Java Code 295Chapter 11: The Inside Story 297A Button-Click Example 297This is a callback 302Android string resources (A slight detour) 302Introducing Inner Classes 307No Publicity, Please! 309Lambda Expressions 313Chapter 12: Dealing with a Bunch of Things at a Time 317Creating a Collection Class 318More casting 320Java generics 321Java’s wrapper classes 325Stepping Through a Collection 326Using an iterator 326The enhanced for statement 328A cautionary tale 329Functional programming techniques 331Java’s Many Collection Classes 332Arrays 333String resource arrays 336Java’s varargs 337Using Collections in an Android App 340The listener 343The adapter 343Chapter 13: An Android Social Media App 345The Twitter App’s Files 346The Twitter4J API jar file 346The manifest file 348The main activity’s layout file 349How to Talk to the Twitter Server 352Using OAuth 353Making a ConfigurationBuilder 353Getting OAuth keys and tokens 355The Application’s Main Activity 357The onCreate method 362The button listener methods 363The trouble with threads 363Understanding Android’s AsyncTask 366My Twitter app’s AsyncTask classes 368Cutting to the chase, at last 370Java’s Exceptions 372Catch clauses 374A finally clause 375Passing the buck 376Chapter 14: Hungry Burds: A Simple Android Game 381Introducing the Hungry Burds Game 382The Main Activity 385The code, all the code, and nothing but the code 388Measuring the display 392Constructing a Burd 395Android animation 398Creating menus 400Shared preferences 403Informing the user 404It’s Been Fun 405Part 5: the Part of Tens 407Chapter 15: Ten Ways to Avoid Mistakes 409Putting Capital Letters Where They Belong 409Breaking Out of a switch Statement 410Comparing Values with a Double Equal Sign 410Adding Listeners to Handle Events 411Defining the Required Constructors 411Fixing Nonstatic References 412Staying within Bounds in an Array 412Anticipating Null Pointers 412Using Permissions 414The Activity Not Found 414Chapter 16: Ten Websites for Developers 415This Book’s Websites 415The Horse’s Mouth 416Finding News and Reviews 416Index 417

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