Efficient Android Threading Asynchronous Processing Techniques for Android Applications

353 Pages·2014·4.95 MB·English

by  Anders Goransson

Efficient Android Threading
Anders Göransson
Dedication
To Anna, Fabian, and Ida.
Preface
Efficient Android Threading explores how to achieve robust and reliable
multithreaded Android applications. We’ll look at the asynchronous mechanisms
that are available in the Android SDK and determine appropriate
implementations to achieve fast, responsive, and well-structured applications.
Let’s face it: multithreading is required to create applications with a great user
experience, but it also increases the complexity of the application and the
likelihood of runtime errors. The complexity partly comes from the built-in
difficulty of execution on multiple threads and from applications that aren’t
utilizing the Android platform efficiently.
This book aims to guide application developers to selecting an asynchronous
mechanism based on an understanding of its advantages and difficulties. By
using the right asynchronous mechanism at the right time, much of the
complexity is transferred from the application to the platform, making the
application code more maintainable and less error prone. As a rule of thumb,
asynchronous execution should not induce more complexity to the code than
necessary, which is achieved through a wise choice from the palette of
asynchronous mechanisms in Android.
Although a high-level asynchronous mechanism can be very convenient to use, it
still needs to be understood — not only used — or the application may suffer
from equally difficult runtime errors, performance degradation, or memory
leaks. Therefore, this book not only contains practical guidelines and examples,
but also explores the underlying enablers for asynchronous execution on
Android.
Audience
This book is for Java programmers who have learned the basics of Android
programming. The book introduces techniques that are fundamental to writing
robust and responsive applications, using standard Android libraries.
Contents of This Book
This book contains two main parts: Part I and Part II. The first part describes the
foundation for threads on Android — i.e., Java, Linux, Handlers — and its
impact on the application. The second part is more hands-on, looking into the
asynchronous mechanisms that an application has at its disposal.
Part I describes how Java handles threads. As an Android programmer, you will
sometimes use these libraries directly, and understanding their behavior is
important for using the higher-level constructs in Part II correctly.
Chapter 1
Explains how the structure of the Android runtime and how the various
components of an Android application affect the use of threads and
multiprocessing.
Chapter 2
Covers the fundamentals of concurrent execution in Java.
Chapter 3
Describes how Android handles threads and how the application threads
execute in the Linux OS. It includes important topics like scheduling and
control groups, as well as their impact on responsiveness.
Chapter 4
Covers basic communication between threads, such as shared memory,
signals, and the commonly used Android messages.
Chapter 5
Shows how Android enhances the IPC mechanisms in Linux with mechanisms
such as RPC and messaging.
Chapter 6
Explains how to avoid leaks, which can cause apps to degrade the system and
be uninstalled by users.
Part II covers the higher-level libraries and constructs in Android that make
programming with threads safer and easier.
Chapter 7
Describes the most basic asynchronous construction, i.e,
java.lang.Thread, and how to handle the various states and problems
that can occur.
Chapter 8
Shows a convenient way to run tasks sequentially in the background.
Chapter 9
Offers techniques for dealing with scheduling, errors, and other aspects of
thread handling, such as thread pools.
Chapter 10
Covers the AsyncTask — probably the most popular asynchronous
technique — and how to use it correctly to avoid its pitfalls.
Chapter 11
Covers the essential Service component, which is useful for functionality
that you want to offer to multiple applications or to keep the application alive
during background execution.
Chapter 12
Builds on the previous chapter with a discussion of a useful technique for
executing off the main UI thread.
Chapter 13
A high-level mechanism that simplifies fast asynchronous access to content
providers.
Chapter 14
Discover how the UI can be updated with loaders, where new data is delivered
asynchronously whenever the content changes.
Chapter 15
Given all the techniques described throughout this book, how do you choose
the right one for your app? This chapter offers guidelines for making this
choice.
Conventions Used in this Book
The following typographical conventions are used in this book:
Italic
Used for emphasis, new terms, URLs, commands and utilities, and file and
directory names.
Constant width
Indicates variables, functions, types, objects, and other programming
constructs.
Constant width italic
Indicates place-holders in code or commands that should be replaced by
appropriate values.
TIP
This element signifies a tip, suggestion, or a general note.
CAUTION
This element indicates a trap or pitfall to watch out for, typically something that isn’t immediately
obvious.
Using Code Examples
Supplemental material (code examples, exercises, etc.) is available for download
at https://github.com/andersgoransson/eatbookexamples.
This book is here to help you get your job done. In general, you may use the
code in this book in your programs and documentation. You do not need to
contact us for permission unless you are reproducing a significant portion of the
code. For example, writing a program that uses several chunks of code from this
book does not require permission. Selling or distributing a CD-ROM of
examples from O’Reilly books does require permission. Answering a question
by citing this book and quoting example code does not require permission.
Incorporating a significant amount of example code from this book into your
product’s documentation does require permission.
We appreciate attribution. An attribution usually includes the title, author,
publisher, and ISBN.
If you believe that your use of code examples falls outside of fair use or the
permission given above, feel free to contact us at [email protected].
Examples will be maintained at:
[email protected]:andersgoransson/eatbookexamples.git
Safari® Books Online
NOTE
Safari Books Online is an on-demand digital library that delivers expert content in both book and video
form from the world’s leading authors in technology and business.
Technology professionals, software developers, web designers, and business and
creative professionals use Safari Books Online as their primary resource for
research, problem solving, learning, and certification training.
Safari Books Online offers a range of product mixes and pricing programs for
organizations, government agencies, and individuals. Subscribers have access to
thousands of books, training videos, and prepublication manuscripts in one fully
searchable database from publishers like O’Reilly Media, Prentice Hall
Professional, Addison-Wesley Professional, Microsoft Press, Sams, Que,
Peachpit Press, Focal Press, Cisco Press, John Wiley & Sons, Syngress, Morgan
Kaufmann, IBM Redbooks, Packt, Adobe Press, FT Press, Apress, Manning,
New Riders, McGraw-Hill, Jones & Bartlett, Course Technology, and dozens
more. For more information about Safari Books Online, please visit us online.