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Head First Java, 2nd Edition

Head First Java, 2nd Edition

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Contents

Table of Contents

Head First Java™

A Note Regarding Supplemental Files

What they’re saying about Head First

Praise for Head First Java

Praise for other Head First books co-authored by Kathy and Bert

Creators of the Head First series

How to Use This Book: Intro

1. Dive in A Quick Dip: Breaking the Surface

2. Classes and Objects: A Trip to Objectville

3. Primitives and References: Know Your Variables

4. Methods Use Instance Variables: How Objects Behave

5. Writing a Program: Extra-Strength Methods

6. Get to Know the Java API: Using the Java Library

7. Inheritance and Polymorphism: Better Living in Objectville

8. Interfaces and Abstract Classes: Serious Polymorphism

9. Constructors and Garbage Collection: Life and Death of an Object

10. Numbers and Statics: Numbers Matter

11. Exception Handling: Risky Behavior

12. Getting GUI: A Very Graphic Story

13. Using Swing: Work on Your Swing

14. Serialization and File I/O: Saving Objects

15. Networking and Threads: Make a Connection

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 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 two 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<Dog> ?

What could happen if it were allowed...

Wildcards to the rescue

Alternate syntax for doing the same thing

17. Package, Jars and Deployment: Release Your Code

18. Remote Deployment with RMI: Distributed Computing

A. Final Code Kitchen

B. The Top Ten Topics that almost made it into the Real Book...

C. This isn’t goodbye

About the Authors

URL

Help

Using a HashSet instead of ArrayList

We added on to the Jukebox to put the songs in a HashSet. (Note: we left out some of the Jukebox code, but you can copy it from earlier versions. And to make it easier to read the output, we went back to the earlier version of the Song’s toString() method, so that it prints only the title instead of title and artist.)

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