Head First Java, 2nd Edition

Table of Contents
Intro.: How to Use This Book
	Who is this book for?
	We know what you’re thinking.
	And we know what your brain is thinking.
	Metacognition: thinking about thinking.
	Here’s what WE did:
	Here’s what YOU can do to bend your brain into submission.
	What you need for this book:
	Last-minute things you need to know:
	Technical Editors
	Other people to credit
	Just when you thought there wouldn’t be anymore acknowledgements*.
Chapter 1. Dive in A Quick Dip: Breaking the Surface
	The Way Java Works
	What you’ll do in Java
	Code structure in Java
	Anatomy of a class
	Writing a class with a main
	Conditional branching
	Coding a Serious Business Application
	Phrase-O-Matic
Chapter 2. Classes and Objects: A Trip to Objectville
	Chair Wars
	Making your first object
	Making and testing Movie objects
	Quick! Get out of main!
	Running the Guessing Game
Chapter 3. Primitives and References: Know Your Variables
	Declaring a variable
	“I’d like a double mocha, no, make it an int.”
	You really don’t want to spill that...
	Back away from that keyword!
	This table reserved.
	Controlling your Dog object
	An object reference is justanother variable value.
	An array is like a tray of cups
	Arrays are objects too
	Make an array of Dogs
	Control your Dog
	A Heap o’ Trouble
Chapter 4. Methods Use Instance Variables: How Objects Behave
	Remember: a class describes what an object knows and what an object does
	The size affects the bark
	You can send things to a method
	You can get things back from a method.
	You can send more than one thing to a method
	Cool things you can do with parameters and return types
	Encapsulation
	Encapsulating the GoodDog class
	How do objects in an array behave?
	Declaring and initializing instance variables
	The difference bet ween instance and local variables
	Comparing variables (primitives or references)
Chapter 5. Writing a Program: Extra-Strength Methods
	Let’s build a Battleship-style game: “Sink a Dot Com”
	First, a high-level design
	The “Simple Dot Com Game” a gentler introduction
	Developing a Class
	The checkYourself() method
	The game’s main() method
	More about for loops
	Trips through a loop
	The enhanced for loop
Chapter 6. Get to Know The Java API: Using the Java Library
	In our last chapter, we left you with the cliff-hanger. A bug.
	So what happened?
	How do we fix it ?
	Option one is too clunky
	Option t wo is a little better, but still pretty clunky
	Wake up and smell the library
	Some things you can do with ArrayList
	Comparing ArrayList to a regular array
	Let’s fix the DotCom code.
	New and improved DotCom class
	Let’s build the REAL game: “Sink a Dot Com”
	What needs to change?
	Who does what in the DotComBust game (and when)
	Prep code for the real DotComBust class
	The final version of the DotCom class
	Super Powerful Boolean Expressions
	Using the Library (the Java API)
	You have to know the full name* of the class you want to use in your code.
	How to play with the API
Chapter 7. Inheritance and Polymorphism: Better Living in Objectville
	Chair Wars Revisited...
	Understanding Inheritance
	Let’s design the inheritance tree for an Animal simulation program
	Using inheritance to avoid duplicating code in subclasses
	Do all animals eat the same way?
	Looking for more inheritance opportunities
	Which method is called?
	Designing an Inheritance Tree
	Using IS-A and HAS-A
	But wait! There’s more!
	How do you know if you’ve got your inheritance right?
	When designing with inheritance, are you using or abusing?
	Keeping the contract: rules for overriding
	Overloading a method
Chapter 8. Interfaces and Abstract Classes
	Did we forget about something when we designed this?
	What does a new Animal() object look like?
	The compiler won’t let you instantiate an abstract class
	Abstract vs. Concrete
	Abstract methods
	You MUST implement all abstract methods
	Polymorphism in action
	Uh-oh, now we need to keep Cats, too.
	What about non-Animals? Why not make a class generic enough to take anything?
	So what’s in this ultra-super-megaclass Object?
	Using polymorphic references of type Object has a price...
	When a Dog won’t act like a Dog
	Objects don’t bark.
	Get in touch with your inner Object.
	What if you need to change the contract?
	Let’s explore some design options for reusing some of our existing classes in a PetShop program.
	Interface to the rescue!
	Making and Implementing the Pet interface
Chapter 9. Constructors and Garbage Collection: Life and Death of an Object
	The Stack and the Heap: where things live
	Methods are stacked
	What about local variables that are objects?
	If local variables live on the stack, where do instance variables live?
	The miracle of object creation
	Construct a Duck
	Initializing the state of a new Duck
	Using the constructor to initialize important Duck state*
	Make it easy to make a Duck
	Doesn’t the compiler always make a no-arg constructor for you?
	Nanoreview: four things to remember about constructors
	Wait a minute... we never DID talk about superclasses and inheritance and how that all fits in with constructors.
	The role of superclass constructors in an object’s life.
	Making a Hippo means making the Animal and Object parts too...
	How do you invoke a superclass constructor?
	Can the child exist before the parents?
	Superclass constructors with arguments
	Invoking one overloaded constructor from another
	Now we know how an object is born, but how long does an object live ?
	What about reference variables?
Chapter 10. Numbers and Statics: Numbers Matter
	MATH methods: as close as you’ll ever get to a global method
	The difference between regular (non-static) and static methods
	What it means to have a class with static methods.
	Static methods can’t use non-static (instance) variables!
	Static methods can’t use non-static methods, either!
	Static variable: value is the same for ALL instances of the class
	Initializing a static variable
	static final variables are constants
	final isn’t just for static variables...
	Math methods
	Wrapping a primitive
	Before Java 5.0, YOU had to do the work...
	Autoboxing: blurring the line between primitive and object
	Autoboxing works almost everywhere
	But wait! There’s more! Wrappers have static utility methods too!
	And now in reverse... turning a primitive number into a String
	Number formatting
	Formatting deconstructed...
	The percent (%) says, “insert argument here”
	The format String uses its own little language syntax
	The format specifier
	The only required specifier is for TYPE
	What happens if I have more than one argument?
	So much for numbers, what about dates?
	Moving backward and forward in time
	Getting an object that extends Calendar
	Working with Calendar objects
	Highlights of the Calendar API
	Even more Statics!... static imports
Chapter 11. Exception Handling: Risky Behavior
	Let’s make a Music Machine
	We’ll start with the basics
	First we need a Sequencer
	What happens when a method you want to call (probably in a class you didn’t write) is risky?
	Methods in Java use exceptions to tell the calling code, “Something Bad Happened. I failed.”
	The compiler needs to know that YOU know you’re calling a risky method.
	An exception is an object... of type Exception.
	If it’s your code that catches the exception, then whose code throws it?
	Flow control in try/catch blocks
	Finally: for the things you want to do no matter what.
	Finally: for the things you want to do no matter what.
	Did we mention that a method can throw more than one exception?
	Exceptions are polymorphic
	Multiple catch blocks must be ordered from smallest to biggest
	You can’t put bigger baskets above smaller baskets.
	When you don’t want to handle an exception...
	Ducking (by declaring) only delays the inevitable
	Getting back to our music code...
	Making actual sound
	Your very first sound player app
	Making a MidiEvent (song data)
	MIDI message: the heart of a MidiEvent
	Change a message
Chapter 12. Getting GUI: A Very Graphic Story
	It all starts with a window
	Your first GUI: a button on a frame
	But nothing happens when I click it...
	Getting a user event
	Listeners, Sources, and Events
	Getting back to graphics...
	Make your own drawing widget
	Fun things to do in paintComponent()
	Behind every good Graphics reference is a Graphics2D object.
	Because life’s too short to paint the circle a solid color when there’s a gradient blend waiting for you.
	We can get an event. We can paint graphics. But can we paint graphics when we get an event?
	GUI layouts: putting more than one widget on a frame
	Let’s try it with TWO buttons
	Inner class to the rescue!
	An inner class instance must be tied to an outer class instance*.
	How to make an instance of an inner class
	Using an inner class for animation
	Listening for a non-GUI event
	An easier way to make messages / events
	Example: how to use the new static makeEvent() method
	Version Two: registering and getting ControllerEvents
	Version Three: drawing graphics in time with the music
Chapter 13. Using Swing: Work on Your Swing
	Swing components
	Layout Managers
	How does the layout manager decide?
	The Big Three layout managers: border, flow, and box.
	Playing with Swing components
	Making the BeatBox
Chapter 14. Serialization and File I/O: Saving Objects
	Capture the Beat
	Saving State
	Writing a serialized object to a file
	Data moves in streams from one place to another.
	What really happens to an object when it’s serialized?
	But what exactly IS an object’s state?What needs to be saved?
	If you want your class to be serializable, implement Serializable
	Deserialization: restoring an object
	What happens during deserialization?
	Saving and restoring the game characters
	Writing a String to a Text File
	Text File Example: e-Flashcards
	Quiz Card Builder (code outline)
	The java.io.File class
	Reading from a Text File
	Quiz Card Player (code outline)
	Parsing with String split()
	Version ID: A Big Serialization Gotcha
	Using the serialVersionUID
	Saving a BeatBox pattern
	Restoring a BeatBox pattern
Chapter 15. Networking and Threads: Make a Connection
	Real-time Beat Box Chat
	Connecting, Sending, and Receiving
	Make a net work Socket connection
	A TCP port is just a number.
	To read data from a Socket, use a BufferedReader
	To write data to a Socket, use a PrintWriter
	The DailyAdviceClient
	DailyAdviceClient code
	Writing a simple server
	DailyAdviceServer code
	Writing a Chat Client
	Java has multiple threads but only one Thread class
	What does it mean to have more than one call stack?
	Every Thread needs a job to do. A method to put on the new thread stack.
	To make a job for your thread, implement the Runnable interface
	The Thread Scheduler
	Putting a thread to sleep
	Using sleep to make our program more predictable.
	Making and starting t wo threads
	What will happen?
	Um, yes. There IS a dark side. Threads can lead to concurrency \'issues\'.
	The Ryan and Monica problem, in code
	We need the makeWithdrawal ( ) method to run as one atomic thing.
	Using an object’s lock
	The dreaded “Lost Update” problem
	Let’s run this code...
	Make the increment() method atomic. Synchronize it!
	The deadly side of synchronization
	New and improved SimpleChatClient
	The really really simple Chat Server
Chapter 16. Collections and Generics: Data Structures
	Tracking song popularity on your jukebox
	Here’s what you have so far, without the sort:
	But the ArrayList class does NOT have a sort() method!
	ArrayList is not the only collection
	You could use a TreeSet... Or you could use the Collections.sort() method
	Adding Collections.sort() to the Jukebox code
	But now you need Song objects, not just simple Strings.
	Changing the Jukebox code to use Songs instead of Strings
	It won’t compile !
	Generics means more type-safety
	Learning generics
	Using generic CLASSES
	Using type parameters with ArrayList
	Using generic METHODS
	Here’s where it gets weird...
	Revisiting the sort( ) method
	In generics, “extends” means“ extends or implements”
	Finally we know what’s wrong... The Song class needs to implement Comparable
	The new, improved, comparable Song class
	We can sort the list, but...
	Using a custom Comparator
	Updating the Jukebox to use a Comparator
	Uh-oh. The sorting all works, but now we have duplicates...
	We need a Set instead of a List
	The Collection API (part of it)
	Using a HashSet instead of ArrayList
	What makes t wo objects equal?
	How a HashSet checks for duplicates: hashCode() and equals()
	The Song class with overridden hashCode() and equals()
	And if we want the set to stay sorted, we’ve got TreeSet
	What you MUST know about TreeSet...
	TreeSet elements MUST be comparable
	We’ve seen Lists and Sets, now we’ll use a Map
	Finally, back to generics
	Using polymorphic arguments and generics
	But will it work with ArrayList ?
	What could happen if it were allowed...
	Wildcards to the rescue
	Alternate syntax for doing the same thing
Chapter 17. Package, Jars and Deployment: Release Your Code
	Deploying your application
	Separate source code and class files
	Put your Java in a JAR
	Running (executing) the JAR
	Put your classes in packages!
	Preventing package name conflicts
	Compiling and running with packages
	The -d flag is even cooler than we said
	Making an executable JAR with packages
	So where did the manifest file go?
	Java Web Start
	The .jnlp file
Chapter 18. Remote Deployment with RMI: Distributed Computing
	Method calls are always between two objects on the same heap.
	What if you want to invoke a method on an object running on another machine?
	Object A, running on Little, wants to call a method on Object B, running on Big.
	But you can’t do that.
	The role of the ‘helpers’
	Java RMI gives you the client and service helper objects!
	How does the client get the stub object?
	How does the client get the stub class?
	Be sure each machine has the class files it needs.
	Yeah, but who really uses RMI?
	What about Servlets?
	Just for fun, let’s make the Phrase-O-Matic work as a servlet
	Phrase-O-Matic code, servlet-friendly
	Enterprise JavaBeans: RMI on steroids
	For our final trick... a little Jini
	Final Project: the Universal Service browser
Appendix A:Final Code Kitchen
	Final BeatBox client program
	Final BeatBox server program
Appendix B: The Top Ten Topics that almost made it into the Real Book...
	#10 Bit Manipulation
	#9 Immutability
	#8 Assertions
	#7 Block Scope
	#6 Linked Invocations
	#5 Anonymous and Static Nested Classes
	#5 Anonymous and Static Nested Classes, continued
	#4 Access Levels and Access Modifiers (Who Sees What)
	#4 Access Levels and Access Modifiers, cont.
	#3 String and StringBuffer/StringBuilder Methods
	#2 Multidimensional Arrays
	#1 Enumerations (also called Enumerated Types or Enums)
Index
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