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    Android: Game Programming
    Android: Game Programming
    Android: Game Programming
    Ebook2,090 pages14 hours

    Android: Game Programming

    By John Horton and Raul Portales

    ()

    Read preview

    About this ebook

    Extend your game development skills by harnessing the power of Android SDK

    About This Book
    • Gain the knowledge to design and build highly interactive and amazing games for your phone and tablet from scratch
    • Create games that run at super-smooth 60 frames per second with the help of these easy-to-follow projects
    • Understand the internals of a game engine by building one and seeing the reasoning behind each of the components
    Who This Book Is For

    If you are completely new to Java, Android, or game programming, this book is for you. If you want to publish Android games for fun or for business and are not sure where to start, then this book will show you what to do, step by step, from the start.

    What You Will Learn
    • Set up an efficient, professional game development environment in Android Studio
    • Explore object-oriented programming (OOP) and design scalable, reliable, and well-written Java games or apps on almost any Android device
    • Build simple to advanced game engines for different types of game, with cool features such as sprite sheet character animation and scrolling parallax backgrounds
    • Implement basic and advanced collision detection mechanics
    • Process multitouch screen input effectively and efficiently
    • Implement a flexible and advanced game engine that uses OpenGL ES 2 to ensure fast, smooth frame rates
    • Use animations and particle systems to provide a rich experience
    • Create beautiful, responsive, and reusable UIs by taking advantage of the Android SDK
    • Integrate Google Play Services to provide achievements and leaderboards to the players
    In Detail

    Gaming has historically been a strong driver of technology, whether we're talking about hardware or software performance, the variety of input methods, or graphics support, and the Android game platform is no different. Android is a mature, yet still growing, platform that many game developers have embraced as it provides tools, APIs, and services to help bootstrap Android projects and ensure their success, many of which are specially designed to help game developers.

    Since Android uses one of the most popular programming languages, Java, as the primary language to build apps of all types, you will start this course by first obtaining a solid grasp of the Java language and its foundation APIs. This will improve your chances of succeeding as an Android app developer. We will show you how to get your Android development environment set up and you will soon have your first working game.

    The course covers all the aspects of game development through various engrossing and insightful game projects. You will learn all about frame-by-frame animations and resource animations using a space shooter game, create beautiful and responsive menus and dialogs, and explore the different options to play sound effects and music in Android. You will also learn the basics of creating a particle system and will see how to use the Leonids library.

    By the end of the course, you will be able to configure and use Google Play Services on the developer console and port your game to the big screen.

    This Learning Path combines some of the best that Packt has to offer in one complete, curated package. It includes content from the following Packt products:

    • Learning Java by Building Android Games by John Horton
    • Android Game Programming by Example by John Horton
    • Mastering Android Game Development by Raul Portales
    Style and approach

    This course is a step-by-step guide where you will learn to build Android games from scratch. It takes a practical approach where each project is a game. It starts off with simple arcade games, and then gradually the complexity of the games keep on increasing as you uncover the new and advanced tools that Android offers.

    LanguageEnglish
    PublisherPackt Publishing
    Release dateSep 26, 2016
    ISBN9781787125780
    Android: Game Programming

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      Book preview

      Android - John Horton

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      Table of Contents

      Android: Game Programming

      Android: Game Programming

      Credits

      Preface

      What this learning path covers

      What you need for this learning path

      Who this learning path is for

      Reader feedback

      Customer support

      Downloading the example code

      Errata

      Piracy

      Questions

      1. Module 1

      1. Why Java, Android, and Games?

      Is this book for me?

      If you just want to learn pure Java

      If Android is your focus

      Where this book will take you

      Why build games to learn to program?

      Why Android and Java?

      Android is the fastest evolving and growing OS ever

      Android developers have great prospects

      Android is open source

      Java is here to stay

      Java is not just for Android

      Java is fast and easy to use

      A summary of Java and Android

      Setting up our development environment

      Installing the JDK

      Android Studio

      Installing Android Studio

      Summary

      2. Getting Started with Android

      Our first game project

      Preparing Android Studio

      Building the project

      Exploring Android Studio

      Using the Android Studio visual designer

      Android UI types

      TextView

      Layout elements

      ImageView widgets

      ButtonView

      Using the sample code

      Making our game menu

      Structuring our code for Android

      Life cycle phases – what we need to know

      Life cycle phases – what we need to do

      Dividing our game into activities

      Our first look at Java

      Cleaning up our code

      Building and installing our game

      Emulators and devices

      Creating an emulator

      Running the emulator

      Running our game on the emulator

      Building our game

      Installing the setup to a device

      Future projects

      Self-test questions

      Summary

      3. Speaking Java – Your First Game

      Java syntax

      The compiler

      Making code clear with comments

      Storing data and using it with variables

      Types of variables

      Reference types

      Declaration

      Initialization

      Changing variables with operators

      Expressing yourself in Java

      Math game – asking a question

      Creating the new game activity

      Laying out the game screen UI

      Coding a question in Java

      Linking our game from the main menu

      Decisions in Java

      More operators

      Decision 1 – If they come over the bridge, shoot them

      Decision 2 – Else, do this

      Switching to make decisions

      Math game – getting and checking the answer

      Self-test questions

      Summary

      4. Discovering Loops and Methods

      Looping with loops

      While loops

      Breaking out of a loop

      The continue keyword

      Do-while loops

      For loops

      Random numbers in Java

      Methods

      The structure of a method

      Modifier

      Return type

      Name of a method

      Parameters

      Getting things done in the method body

      Using methods

      A working method

      Exploring method overloading

      Enhancing our math game

      Enhancing the UI

      The new Java code

      Amending GameActivity

      The methods

      The setQuestion method

      The updateScoreAndLevel method

      The isCorrect method

      Calling our new methods

      Finishing touches

      Going full screen and locking orientation

      Adding a custom image (instead of the Android icon)

      Self-test questions

      Summary

      5. Gaming and Java Essentials

      Java arrays – an array of variables

      Arrays are objects

      A simple example of an array

      Getting dynamic with arrays

      Dynamic array example

      Entering the nth dimension with arrays

      An example of a multidimensional array

      Array-out-of-bounds exceptions

      Timing with threads

      A simple thread timer example with the Handler class

      Beeps n buzzes – Android sound

      Creating sound FX

      Playing sounds in Android

      Life after destruction – persistence

      An example of persistence

      The memory game

      Phase 1 – the UI and the basics

      Phase 2 – preparing our variables and presenting the pattern

      Phase 3 – the player's response

      Phase 4 – preserving the high score

      Animating our game

      UI animation in Android

      Phase 5 – animating the UI

      Self-test questions

      Summary

      6. OOP – Using Other People's Hard Work

      What is OOP?

      Why do it like this?

      Our first class and first object

      Basic classes

      More things we can do with our first class

      Encapsulation

      Controlling the use of classes with access modifiers

      Class access in a nutshell

      Controlling the use of variables with access modifiers

      Variable access in a nutshell

      Methods have access modifiers too

      Method access in a nutshell

      Accessing private variables with the getter and setter methods

      Setting up our objects with constructors

      Variables revisited

      The stack and the heap

      A quick break to throw out the trash

      Access, scope, this, static, and constructors demo

      A quick summary on stack and heap

      Inheritance

      An example of inheritance

      Polymorphism

      Abstract classes

      Interfaces

      More about OOP and classes

      Inner classes

      Self-test questions

      Summary

      7. Retro Squash Game

      Drawing with Android Canvas

      The Android coordinate system

      Animating our pixels

      Getting started with Canvas and Paint

      Android Canvas demo app

      Detecting touches on the screen

      Preparing to make the retro squash game

      The design of the game

      The UI

      Physics

      The structure of the code

      The four implementation phases in detail

      Phase 1 – MainActivity and onCreate

      Phase 1 code explained

      Phase 2 – SquashCourtView part 1

      Phase 2 code explained

      Phase 3 – SquashCourtView part 2

      Phase 3 code explained

      Phase 4 – Remaining lifecycle methods

      Good object-oriented design

      Self-test questions

      Summary

      8. The Snake Game

      Game design

      The coordinate system

      Keeping track of the snake segments

      Detecting collisions

      Drawing the snake

      The code structure

      MainActivity

      GameActivity

      Tidying up onCreate

      Animation, sprite sheets, and the Snake home screen

      Animating with sprite sheets

      Implementing the Snake home screen

      Implementing the Snake game activity

      Enhancing the game

      Self-test questions

      Summary

      9. Making Your Game the Next Big Thing

      How to publish your app

      Marketing your app

      Adding leaderboards and achievements

      Planning the Snake achievements

      Step-by-step leaderboards and achievements

      Installing the Google Play Services API on your PC

      Configuring the Google Play developer console

      Implementing the leaderboard in the Google Play developer console

      Implementing the achievements in the Google Play developer console

      Setting up the Snake project ready for implementation

      Implementing the player's sign-in, achievements, and leaderboard buttons

      Implementing the leaderboards in code

      Implementing the achievements in code

      Uploading the updated Snake game to Google Play

      What next?

      Getting a programmer's job

      Building bigger and better games

      Self-test questions

      Summary

      A. Self-test Questions and Answers

      Chapter 2

      Chapter 3

      Chapter 4

      Chapter 5

      Chapter 6

      Chapter 7

      Chapter 8

      Chapter 9

      2. Module 2

      1. Player 1 UP

      A closer look at the games

      Tappy Defender

      Tough retro platformer

      Asteroids simulator

      Setting up your development environment

      Installing the JDK

      Installing Android Studio

      Summary

      2. Tappy Defender – First Step

      Planning the first game

      Backstory

      The game mechanics

      Rules for the game

      The design

      Control

      Model

      View

      Design pattern reality check

      The game code structure

      The Android Activity lifecycle

      The Android Studio file structure

      Building the home screen

      Creating the project

      What we did

      Building the home screen UI

      What we did

      Coding the functionality

      Creating GameActivity

      What we did

      Configuring the AndroidManifest.xml file

      What we did

      Coding the game loop

      Building the view

      Creating a new class for the view

      What we did

      Structuring the class code

      The game activity

      The PlayerShip object

      Drawing the scene

      Plotting and drawing

      Drawing PlayerShip

      The Canvas and Paint objects

      Controlling the frame rate

      Deploying the game

      Debugging on an Android device

      Summary

      3. Tappy Defender – Taking Flight

      Controlling the spaceship

      Detecting touches

      Adding boosters to the spaceship

      Detecting the screen resolution

      Building the enemies

      Designing the enemy

      Spawning the enemy

      Making the enemy think

      The thrill of flight – scrolling the background

      Things that go bump – collision detection

      Collision detection options

      Rectangle intersection

      Radius overlapping

      The crossing number algorithm

      Optimizations

      Multiple hitboxes

      Neighbor checking

      Best options for Tappy Defender

      Summary

      4. Tappy Defender – Going Home

      Displaying a HUD

      Implementing the rules

      Ending the game

      Restarting the game

      Adding sound FX

      Generating the FX

      The SoundPool class

      Coding the sound FX

      Adding persistence

      Iteration

      Multiple different enemy graphics

      An exercise in balance

      Format time

      Handle the back button

      The finished game

      Summary

      5. Platformer – Upgrading the Game Engine

      The game

      The backstory

      The game mechanics

      Rules for the game

      Upgrading the game engine

      The platform activity

      Locking the layout to landscape

      The PlatformView class

      The basic structure of PlatformView

      The GameObject class

      The view through a viewport

      Creating the levels

      The enhanced update method

      The enhanced draw method

      Summary

      6. Platformer – Bob, Beeps, and Bumps

      The SoundManager class

      Introducing Bob

      Multiphase collision detection

      Player input

      Animating Bob

      Summary

      7. Platformer – Guns, Life, Money, and the Enemy

      Ready aim fire

      Pickups

      The drone

      The guard

      Summary

      8. Platformer – Putting It All Together

      Bullet collision detection

      Adding some fire tiles

      Eye candy

      The new platform tiles

      The new scenery objects

      Scrolling parallax backgrounds

      Pause menu with moveable viewport

      Levels and game rules

      Traveling between levels

      The level designs

      The cave

      The city

      The forest

      The mountains

      The HUD

      Summary

      9. Asteroids at 60 FPS with OpenGL ES 2

      Asteroids simulator

      The game controls

      Rules for the game

      Introducing OpenGL ES 2

      Why use it and how does it work?

      What is neat about Version 2?

      How we will use OpenGL ES 2?

      Preparing OpenGL ES 2

      Locking the layout to landscape

      Activity

      The view

      A class to manage our game

      Managing simple shaders

      The game's main loop – the renderer

      Building an OpenGL-friendly, GameObject super class

      The spaceship

      Drawing at 60 + FPS

      Summary

      10. Move and Draw with OpenGL ES 2

      Drawing a static game border

      Twinkling stars

      Bringing the spaceship to life

      Rapid fire bullets

      Reusing existing classes

      Adding the SoundManager class

      Adding the InputController class

      Drawing and moving the asteroids

      Scores and the HUD

      Adding control buttons

      Tally icons

      Life icons

      Declaring, initializing, and drawing the HUD objects

      Summary

      11. Things That Go Bump – Part II

      Planning for collision detection

      Colliding with the border

      The first phase of border collision detection

      Colliding with an asteroid

      The crossing number

      The first phase and overview of asteroid collision detection

      The CollisionPackage class

      Adding collision packages to the objects and making them accessible

      Adding a collision package to the Bullet class

      Adding a collision package to the SpaceShip class

      Adding a collision package to the Asteroid class

      The CD class outline

      Implementing radius overlapping for asteroids and ships

      Implementing rectangle intersection for the border

      Performing the checks

      Helper methods

      Destroying a ship

      Destroying an asteroid

      Testing for collisions in update()

      Precise collision detection with the border

      Precise collision detection with an asteroid

      Finishing touches

      Summary

      3. Module 3

      1. Setting Up the Project

      The right tool for the right game

      Do you want to use 3D?

      Do you want to use physics?

      Do you want to use Java?

      Pros of building games with the Android SDK

      Cons of building games with the Android SDK

      I want the Android SDK!

      The project – YASS (Yet Another Space Shooter)

      Activities and Fragments

      Project setup

      Creating the stub project

      Cleaning up

      Choosing an orientation

      Dealing with aspect ratios

      Game architecture

      GameEngine and GameObjects

      Starting a game

      Stopping a game

      Managing game objects

      UpdateThread

      DrawThread

      User input

      Putting everything together

      Moving forward with the example

      Handling the back key

      Honoring the lifecycle

      Using as much screen as we can

      Before Android 4.4 – almost fullscreen

      Android 4.4 and beyond – immersive mode

      Putting fullscreen together

      Good practices for game developers

      Object pools

      Avoiding enhanced loop syntax in lists

      Precreating objects

      Accessing variables directly

      Being careful with floating points

      Performance myths – avoid interfaces

      Summary

      2. Managing User Input

      The InputController base class

      The Player object

      Displaying a spaceship

      Firing bullets

      The Bullet game object

      The most basic virtual keypad

      Limitations and problems

      Creating a virtual joystick

      General considerations and improvements

      Physical controllers

      Handling MotionEvents

      Handling KeyEvents

      Detecting gamepads

      Sensors and InputControllers

      Selecting control modes

      Summary

      3. Into the Draw Thread

      Using GameView

      The GameView interface

      StandardGameView

      SurfaceGameView

      Updating GameEngine

      Updating the game layout

      Improving DrawThread

      Sprites

      Updating the spaceship and bullets

      Adding a frames-per-second (fps) counter

      Spawning enemies – the GameController

      Procedural/random

      Deterministic/static

      Hybrid approach

      Our approach

      The asteroids

      More on the transformation matrix

      Occlusion culling

      Parallax backgrounds

      Multiple backgrounds

      Layers

      Summary

      4. Collision Detection

      Detecting collisions

      Who can collide?

      Updating GameEngine

      Handling collisions

      Rectangular bodies

      Adding visual feedback

      Pros and cons

      Circular bodies

      Adding visual feedback

      Pros and cons

      Mixed collision detection

      Adding visual feedback

      Other options for shapes

      Optimization

      Spatial partitioning and QuadTree

      Duplicated collisions

      Summary

      5. Particle Systems

      General concepts

      Particles

      ParticleSystem

      Initializers

      Modifiers

      Composite GameObjects and GameEngine

      Making good particle systems

      One shot

      Asteroid explosions

      Spaceship explosions

      Emitters

      Asteroid trails

      The spaceship's engine

      Summary

      6. Sound FX and Music

      SoundManager

      Sound FX

      How to create sound FXs

      GameEvents

      Using SoundPool

      Playing music

      Obtaining music

      MediaPlayer

      Music and Activity life cycle

      Enabling and disabling music and sound FX

      Updating MainMenuFragment

      Updating SoundManager

      Disabling system sounds

      Summary

      7. Menus and Dialogs

      Custom fonts

      Working with backgrounds

      The power of XML drawables

      State list drawables

      State lists colors

      Shape drawables

      The GameFragment

      Adding a score

      Adding lives

      Custom dialogs

      BaseCustomDialog

      Quit dialog

      Pause dialog

      Game Over dialog

      Other dialogs

      Designing for multiple screen sizes

      Summary

      8. The Animation Framework

      Updating BaseFragment

      AnimationDrawable

      Animated sprites

      Animating views

      XML versus code

      Interpolators

      View animation

      Animating dialogs

      Delaying the action in the dialogs to onDismissed

      Pulsating buttons

      Property animation

      ViewPropertyAnimator

      Moving a spaceship around

      Animating the main menu

      Summary

      9. Integrating Google Play Services

      Setting up the developer console

      Setting up the code

      Achievements

      Architecture

      Unlocking achievements

      Leaderboards

      Opening the Play Games UI

      Other features of Google Play services

      Events

      Quests

      Gifts

      Saved games

      Multiplayer games

      Summary

      10. To the Big Screen

      Project configuration

      Testing for Android TV

      Declaring a TV Activity

      Providing a home screen banner

      Declaring it as a game

      Declaring Leanback support

      Declaring touchscreen capability as not required

      Reviewing the manifest

      Showing controller instructions

      Dealing with overscan

      Controller-based navigation

      Dialogs and controllers

      Beyond this book

      Summary

      A. API Levels for Android Versions

      A. Bibliography

      Index

      Android: Game Programming

      Android: Game Programming

      Extend your game development skills by harnessing the power of Android SDK

      A course in three modules

      Android: Game Programming

      BIRMINGHAM - MUMBAI

      Android: Game Programming

      Copyright © 2016 Packt Publishing

      All rights reserved. No part of this course may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.

      Every effort has been made in the preparation of this course to ensure the accuracy of the information presented. However, the information contained in this course is sold without warranty, either express or implied. Neither the authors, nor Packt Publishing, and its dealers and distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this course.

      Packt Publishing has endeavored to provide trademark information about all of the companies and products mentioned in this course by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.

      Published on: September 2016

      Published by Packt Publishing Ltd.

      Livery Place

      35 Livery Street

      Birmingham B3 2PB, UK.

      ISBN 978-1-78712-858-3

      www.packtpub.com

      Credits

      Authors

      John Horton

      Raul Portales

      Reviewers

      Tony Atkins

      Thorsten Harbig

      Boon Hian Tek

      Håvard Kindem

      José Rodriguez-Rivas

      Sergio Viudes Carbonell

      Antonio Hernández Niñirola

      Content Development Editor

      Arun Nadar

      Production Coordinator

      Melwyn Dsa

      Preface

      Android is the fastest growing operating system, and Android devices can empower, entertain, and educate the planet. Android uses one of the most popular programming languages—Java, which is a high-performance, secure, and object-oriented language.

      It is the most widespread Operating System and games are what people spend most time using on their phones. Video games have never been easier to make and distribute. Who would not want to make games for Android? And on top of this, making games is fun, addictive, and very rewarding; it can be hard to stop once you get started.

      The problem comes when we reach a stumbling block because we don't know how to implement a feature, or perhaps integrate it into our game. This course will help you build simple as well as complex games from scratch using the Android SDK and all your queries and obstacles will be addressed in this journey.

      Let's get rolling!

      What this learning path covers

      Module 1, Learning Java by Building Android Games, starts off with the Java fundamentals and their use in an Android environment to make a simple math quiz game. You will be building your very own Android UI using easy to-use tools in Android Studio. You will learn to add real-time interaction with Java threads and implement locking/handling screen rotation, pixel graphics, clicks, animation, sound FX, and many other features in your games. It also covers the advanced OOP concepts for building and deploying a graphical pong-style game. This module ends with exploring different APIs and implement advanced features such as online leaderboards and achievements using Google game services

      Module 2, Android Game Programming by Example, is a whirlwind tour of as many Android 2D gaming features that can possibly be squeezed into 11 chapters. Every line of the code used to build three games of increasing difficulty is shown in the text of this module and explained in a straightforward manner. It is steadily built up to implement a flexible and advanced game engine that uses OpenGL ES 2 for fast smooth frame rates. This is achieved by starting with a simple game and gradually increasing the complexity of the three complete games built step by step. You will implementing cool features like sprite sheet character animation and scrolling parallax backgrounds and be designing and implementing genuinely challenging and playable platform game levels. You will then learn to code both basic and advanced collision detection and make the math behind 2D rotation, velocity, and collision simple. Later on you will learn how to run your game designs at 60 frames per second or better and also process multi-touch screen input. By the end of this module, you will be implementing a multitude of other game features like pickups, firing weapons, HUDs, generating and playing sound FX, scenery, level transition, high scores, and more.

      Module 3, Mastering Android Game Development, will help you build a real-time game from scratch using the Android SDK. This module will make you understand the internals of a game engine and each of its components. You will learn to decide when to use each of the different ways of drawing on Android. Moving forward, you will learn to handle user inputs, from virtual joysticks to gamepads, collision detection using different techniques and discover how to optimize it for complex games. You will also learn about animations and particle system and how to implement it in your game before you finally move on to tackle the challenges faced while making it available on Google play for Android TV.

      What you need for this learning path

      Any recent and free version of Eclipse or Android Studio running on any of the major operating systems can use the code in this course.

      Android Studio is the recommended development tool, and at time of publication, the minimum system requirements are:

      For Windows:

      Microsoft Windows 8/7/Vista/2003 (32 or 64-bit)

      GB RAM minimum, 4 GB RAM recommended

      400 MB hard disk space

      At least 1 GB for Android SDK, emulator system images, and caches

      1280 x 800 minimum screen resolution

      Java Development Kit (JDK) 7

      Optional for accelerated emulator: Intel processor with support for Intel VTx, Intel EM64T (Intel 64), and Execute Disable (XD) Bit functionality

      For Mac OS X:

      Mac OS X 10.8.5 or higher, up to 10.9 (Mavericks)

      2 GB RAM minimum, 4 GB RAM recommended

      400 MB hard disk space

      At least 1 GB for Android SDK, emulator system images, and caches

      1280 x 800 minimum screen resolution

      Java Runtime Environment (JRE) 6

      Java Development Kit (JDK) 7

      Optional for accelerated emulator: Intel processor with support for Intel VTx, Intel EM64T (Intel 64), and Execute Disable (XD) Bit functionality

      On Mac OS, run Android Studio with Java Runtime Environment (JRE) 6 for optimized font rendering. You can then configure your project to use JDK 6 or JDK 7.

      For Linux:

      GNOME or KDE desktop

      GNU C Library (glibc) 2.15 or later

      2 GB RAM minimum, 4 GB RAM recommended

      400 MB hard disk space

      At least 1 GB for Android SDK, emulator system images, and caches

      1280 x 800 minimum screen resolution

      Oracle Java Development Kit (JDK) 7

      Tested on Ubuntu 14.04, Trusty Tahr (64-bit distribution capable of running 32-bit applications).

      Who this learning path is for

      If you are completely new to any one of Java, Android, or game programming, this book is for you. If you want to publish Android games for fun or for business and are not sure where to start, then this book will show you what to do, step by step from the start.

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      Questions

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      Part 1. Module 1

      Learning Java by Building Android Games

      Get ready for a fun-filled experience of learning Java by developing games for the Android platform

      Chapter 1. Why Java, Android, and Games?

      Welcome to Learning Java by Building Android Games, which I hope is just the beginning of your exciting journey into designing and writing games. By the end of this book, we will have made four complete games: a math quiz with dynamically increasing difficulty, a memory game in the style of the classic Simon toy, a pong-style squash game, and a clone of the classic Snake game.

      Besides these games, we will build more than a dozen working apps to practice and demonstrate individual concepts to aid our learning of Java, Android, and games. Our games and apps will feature sound FX, graphics, and animations. We will learn everything from using the standard Android User Interface (UI) designer to creating smooth animations by plotting individual pixels.

      Although I will encourage you to work with me and implement the specific projects that are detailed step by step throughout the book, I fully expect that once you grasp the different concepts, you will want to use them in your own unique creations without delay. This is exactly what I hope you will be inspired to do.

      The game projects themselves are not the objective of the book but the means to a much loftier goal. By the end of the book, you will be able to design and implement your own 2D Android games, to sell or just to give away, on Google Play.

      Tip

      There is a bit of ground work to cover first, but I promise it won't take long and it won't be complicated either. Anyone can learn to program.

      However, there are so many differing opinions among experts, which breeds confusion among beginners concerning the best ways of learning to program. So it is a good idea to look at why learning Java, Android, and games is an ideal pathway for beginners. This will be the first thing we will discuss in this book.

      Here is what we will learn in this chapter:

      Is this book for me?

      Why should I use games to learn to program?

      Why should I learn Java and Android?

      Setting up our development environment

      Is this book for me?

      If you have already decided that Java, Android, or games are what you want to learn, then the next question might be, Is this specific book for me?.

      There are plenty of Java books for beginners and books by much more accomplished authors and programmers than myself. I have read many of them and admire the authors. However, when these books drift away—which they all do—to topics such as Java-native interfaces, web browser applets, or server-side remote communication, I sometimes find myself questioning their immediate relevance to me.

      At this point, at least subconsciously, my commitment would wane and the learning process would slow or stop.

      If you just want to learn pure Java

      If you just want to learn Java on its own, this book will be a solid start. Although the Android stuff might be considered overhead to your pure Java learning, this is much less than the multitude of potentially unnecessary topics that would be introduced in any other Java book. The only caveat with this book is that the necessary overhead is all at the beginning. But once this minimal overhead is cleared, we can focus quite intently on Java.

      With regard to the amount of overhead:

      It will take about six pages to set up our programming environment in this chapter

      It will take Chapter 2, Getting Started with Android, to get familiar with the Android tools, create your first working project, and glimpse your first real Java code

      From then on, it will be nearly pure Java and building games

      You will soon see that the tiny amount of overhead is not excessive and is well worthwhile.

      If Android is your focus

      If it was Android itself that made you look at this book, then I am proud to say this is the first book that will teach you Android without assuming you have any prior Java or programming knowledge whatsoever.

      Where this book will take you

      By the end of this book, you will be able to easily take one of many paths including these:

      Learning Java at a higher level for any platform

      Intermediate level Android learning including pure game frameworks (which will be covered in more detail in Chapter 9, Making Your Game the Next Big Thing)

      A higher level of games development

      Much easier tackling of any modern object-oriented language for things such as iOS, Windows, or web development

      So if you know you want to learn Android or Java, hopefully, I have gone some way to make you commit to the way this book will help you. But why games, Android, or Java at all?

      Why build games to learn to program?

      Fun, of course! But there are other reasons too. Successfully running any program we have written is immensely satisfying, even more so when it involves using some code that we previously didn't understand.

      But making our own games, as you will soon realize, creates a feeling of pleasure that is not easy to describe—it has to be experienced. Then there are added bonuses of sharing our creations with friends on a phone or tablet or even sharing them publicly on the Google Play Store, and you might realize that once you start making games, you can't stop.

      As we create more complex games steadily, you'll realize that all techniques and pieces of code can be rehashed to create other games, and you can then start planning your very own unique masterpieces. This is exhilarating to say the least.

      And as with many subjects, the more we practice the better we get. So games are a perfect way to start learning to program Java. However, most beginners' books for Android games require a fairly high level of Java knowledge. But as we will see, it is perfectly possible to keep the practical examples as fun game projects and still start with the very basics of Java.

      There is a slight trade-off in doing things this way. We will not always approach the working game examples in a by-the-book manner. This is to avoid the problem of doing cartwheels before mastering the forward roll.

      The learning outcome priority will always be the Java programming concept, followed by understanding the Android environment and game design principles. Having said that, we will closely examine and practice plenty of Android and game programming fundamentals.

      Of course, from what we have just discussed, you can probably surmise that it would have been possible to teach a bit more Java in the same number of pages if we hadn't been making games.

      This is true, but then we lose all the benefits that come with using games as the subject matter. Making games really can be a joy, and when our brains are open and eager for information, we will learn much faster. The minimal overhead of learning this way is negated a hundred times over. If games don't interest you in the slightest, then there are plenty of Java beginners' guides out there that take the traditional approach. Just don't expect quite the same thrill as when you publish your first game with online leaderboards and achievements.

      Why Android and Java?

      A part of successful learning is the commitment by the student, not just to do the work, but in their belief that they are doing the right thing in the right way. So many technology-based courses and books don't get that commitment from the reader, not subconsciously anyway.

      The problem is the students' belief that they might be, partly at least, wasting their time with something that is or will soon become outdated or perhaps is not quite right for them. This can be true to a large extent with programming. So why should you spend your finite time learning Java, on Android?

      Android is the fastest evolving and growing OS ever

      At one time, Android updates emerged almost every two months. Even now, they emerge about once in six months. By comparison, Windows takes years between versions and even iOS updates come only yearly and usually change relatively little between versions. Android is obviously evolving and improving at an unprecedented rate.

      Tip

      Look at the history of Android versions since Version 1 at http://www.cnet.com/news/history-of-android/.

      The first humble version of Android was released in 2008, around the same time when consumers were already quite excited about the then much flashier iPhone. News stories were also reporting that developers were getting rich by selling apps in the iTunes app store.

      But in the last full year before this book was written, Samsung alone shipped more Android units than Apple sold all iOS devices combined. I am not joining the war on whose devices are best. I enjoy aspects of both Android and Apple, but purely in terms of picking a platform to learn on, you are probably in the right place at the right time with Android.

      Android developers have great prospects

      Now you might have picked up this book just for the fun and satisfaction that comes with learning to program games. But if you decide to develop your learning further, you will find that the demand for Android programmers is enormous and therefore very lucrative too.

      Tip

      Some data suggests salaries in excess of 100,000 US dollars. For more information, go to http://www.indeed.com/salary?q1=Android+Developer&l1=United+States.

      Android is open source

      What open source means is that although Google develops all the flavors of Android that are used on the newest devices, once the code is released, anybody can do whatever they like with it. Google only exerts control for a limited amount of time.

      In practice, most Android users have the pure Google OS or the modified versions turned out by big manufacturers such as Samsung and HTC, but there is nothing to stop anybody taking the OS and changing, adapting, or converting it into whatever they like. In short, Android could never be taken away from the programming community.

      Java is here to stay

      Okay, so we see Android isn't likely to disappear but could Java become redundant? And will your significant time investment be wasted? On Android, as with most platforms, you can use many languages and tools. Android, however, was designed from the ground up to facilitate Java development. All other languages and tools are not invalid but tend to serve a fairly specific purpose, rather than be a real alternative to Java. In fact, as far as games are concerned, many of the alternatives to a pure Java development environment are also Java-based and require a good level of skill in Java to use. For example, the popular LibGDX game development library, which allows you to simultaneously make games for Android, iOS, Windows, Linux, Mac and even the Web, still uses Java! We will talk more about this in Chapter 9, Making Your Game the Next Big Thing. The point is that Java and Android are tied together and will likely thrive together.

      Java is not just for Android

      Java has been around a lot longer than Android, since the beginning of the 1990s in fact. Although what Java has been used for has evolved and diversified over more than two decades, the originally implemented strengths of the language itself remain the same today.

      Java was designed to be platform- or computer-independent. This is achieved by the use of a virtual machine (VM). This is a program written in another language that decodes the Java program that we write and interacts with the computer platform it is running on. So as long as there is a VM for the computer you want to run your Java program on, with a few caveats, your Java program will work. So if you learn Java, you are learning a language that is used everywhere from the smart fridge to the Web and most places in between.

      It is true, however, that the VM on each platform can and usually does implement features to specifically suit the uses it is likely to be put to. A clear example of this would be mobile-device-specific features such as sensors, GPS, or the built-in camera on many Android devices. Using Java with Android, you can take photos, detect the air pressure, and work out exactly where in the world you are. Most fridge VMs probably will not do this. So you can't always just run a Java program designed for device x on device y, but the language and syntax is the same. Learning Java on Android prepares you in a large part for Java in any situation. So rest assured that Java isn't going away any time soon.

      Java is fast and easy to use

      There is a decades-long debate over which language is the best overall or which language is the best to learn programming. Critics of Java will likely say things about Java's speed. It is true that the Java memory management along with the VM interpretation process does have some speed cost. However, these things have benefits; they significantly improve our productivity and the way that the Android VM interacts with a device largely negates the minor speed penalty. And since Android 4.4, it does so completely with Android Run Time (ART), which installs apps written in Java as fully native applications. Now Java programmers can build games in a friendly, interpreted language and have them run as if they were written in a more challenging natively compiled language.

      A summary of Java and Android

      In a rapidly changing world, if you are worried about where to invest your precious learning time, it is hard to have more confidence. Here we have a language (Java) whose fundamentals have remained almost the same for nearly a quarter of a century, and a platform (Android) that is backed by the biggest names in hardware, software, and retail, and though it's admittedly hugely influenced, it's not actually owned by anyone.

      I am not an evangelist of any technology over another although it is true that I love doing stuff on Android. But you can be sure in your mind that if you are considering the best path to begin learning programming, there is a very strong argument that Java and Android are the best choice.

      If you want to learn Java for any of its numerous uses, then this is a very good place to start. If you want to develop for Android or get into Android development of any sort, then Java is the absolute fundamental way to start, and making games has the enormous benefits we have already discussed.

      By the end of the book, you will be able to write Java code for almost any Java-supported platform. You will be able use almost everything you learn in this book, away from the Android environment.

      If you are planning to pursue a career or business by making Android games or any Android apps, then this book is possibly the only place to start for beginners.

      If you are completely new to Java and want the easiest possible path to mastering it—the fastest growing platform on the planet—then Learning Java by Building Android Games will probably be just right for you.

      So hopefully you are assured that the path this book will take to learn Java is as easy, fun, and thorough as learning Java can be. Let's get set up so we can start building games.

      Setting up our development environment

      The first thing we need to do is prepare our PC to develop for Android using Java. Fortunately, this is made quite simple for us.

      Tip

      If you are learning on Mac or Linux, everything in this book will still work. The next two tutorials have Windows-specific instructions and screenshots. However, it shouldn't be too difficult to vary the steps slightly to suit Mac or Linux.

      All we need to do is:

      Install a software package called the Java Development Kit (JDK), which allows us to develop in Java.

      Install Android Studio, a program designed to make Android development fast and easy. Android Studio uses the JDK and some other Android-specific tools that automatically get installed when we install Android Studio.

      Installing the JDK

      The first thing we need to do is get the latest version of the JDK. To complete this guide, perform the following steps:

      You need to be on the Java website, so visit http://www.oracle.com/technetwork/java/javase/downloads/index.html.

      Find the three buttons shown in the following screenshot and click on the one that says JDK (highlighted). They are on the right-hand side of the web page. Click on the DOWNLOAD button under the JDK option:

      Installing the JDK

      You will be taken to a page that has multiple options to download the JDK. In the Product/File description column, you need to click on the option that matches your operating system. Windows, Mac, Linux and some other less common options are all listed.

      A common question here is, do I have 32- or 64-bit windows?. To find out, right-click on your My Computer (This PC on Windows 8) icon, click on the Properties option, and look under the System heading in the System type entry, as shown in the following screenshot:

      Installing the JDK

      Click on the somewhat hidden AcceptLicense Agreement checkbox:

      Installing the JDK

      Now click on the download option for your OS and system type as previously determined. Wait for the download to finish.

      In your Downloads folder, double-click on the file you just downloaded. The latest version at time of writing this for a 64-bit Windows PC was jdk-8u5-windows-x64. If you are using Mac/Linux or have a 32-bit OS, your filename will vary accordingly.

      In the first of several install dialogs, click on the Next button and you will see the next dialog box:

      Installing the JDK

      Accept the defaults shown in the previous screenshot by clicking on Next. In the next dialog box, you can accept the default install location by clicking on Next.

      Next is the last dialog of the Java installer. Click on Close.

      The JDK is now installed. Next we will make sure that Android Studio is able to use the JDK.

      Right-click on your My Computer (This PC on Windows 8) icon and navigate to Properties | Advanced system settings | Environment variables | New (under System variables, not under User variables). Now you can see the New System Variable dialog, as shown in the following screenshot:

      Installing the JDK

      Type JAVA_HOME for Variable name and enter C:\Program Files\Java\jdk1.8.0_05 for the Variable value field. If you installed the JDK somewhere else, then the file path you enter in the Variable value: field will need to point to wherever you put it. Your exact file path will likely have a different ending to match the latest version of Java at the time you downloaded it.

      Click on OK to save your new settings. Now click on OK again to clear the Advanced system settings dialog.

      Now we have the JDK installed on our PC. We are about half way towards starting to learn Java programming, but we need a friendly way to interact with the JDK and to help us make Android games in Java.

      Android Studio

      We learned that Android Studio is a tool that simplifies Android development and uses the JDK to allow us to write and build Java programs. There are other tools you can use instead of Android Studio. There are pros and cons in them all. For example, another extremely popular option is Eclipse. And as with so many things in programming, a strong argument can be made as to why you should use Eclipse instead of Android Studio. I use both, but what I hope you will love about Android Studio are the following elements:

      It is a very neat and, despite still being under development, a very refined and clean interface.

      It is much easier to get started compared to Eclipse because several Android tools that would otherwise need to be installed separately are already included in the package.

      Android Studio is being developed by Google, based on another product called IntelliJ IDEA. There is a chance it will be the standard way to develop Android in the not-too-distant future.

      Tip

      If you want to use Eclipse, that's fine; all of the code in this book will work. However, some the keyboard shortcuts and user interface buttons will obviously be different. If you do not have Eclipse installed already and have no prior experience with Eclipse, then I even more strongly recommend you to go ahead with Android Studio.

      Installing Android Studio

      So without any delay, let's get Android Studio installed and then we can begin our first game project. To do this, let's visit https://developer.android.com/sdk/installing/studio.html.

      Click on the button labeled Download Android Studio to start the Android studio download. This will take you to another web page with a very similar-looking button to the one you just clicked on.

      Accept the license by checking in the checkbox, commence the download by clicking on the button labeled Download Android Studio for Windows, and wait for the download to complete. The exact text on the button will probably vary depending on the current latest version.

      In the folder in which you just downloaded Android Studio, right-click on the android-studio-bundle-135.12465-windows.exe file and click on Run as administrator. The end of your filename will vary depending upon the version of Android Studio and your operating system.

      When asked if you want to Allow the following program from an unknown publisher to make changes to your computer, click on Yes. On the next screen, click on Next.

      On the screen shown in the following screenshot, you can choose which users of your PC can use Android Studio. Choose whatever is right for you as all options will work, and then click on Next:

      Installing Android Studio

      In the next dialog, leave the default settings and then click on Next.

      Then on the Choose start menu folder dialog box, leave the defaults and click on Install.

      On the Installation complete dialog, click on Finish to run Android Studio for the first time.

      The next dialog is for users who have already used Android Studio, so assuming you are a first time user, select the I do not have a previous version of Android Studio or I do not want to import my settings checkbox, and then click on OK:

      Installing Android Studio

      That was the last piece of software we needed. The simple nine-step process we just went through has actually set up a whole range of Android tools that we will begin to use in the next chapter.

      Summary

      We discussed why games, Java, and Android are not only extremely exciting but also arguably the best way to learn to program. This is because games can be an extremely motivating subject matter and Java and Android have enormous strengths with regards to popularity and longevity, and are open to all of us to use for free.

      We also set up the Java development kit and installed Android Studio, getting ready for the next chapter where we will actually create a part of a working game and take our first look at some Java code.

      Chapter 2. Getting Started with Android

      In this chapter, we will take a roller coaster ride through all the Android topics that you need to learn in order to get started with Java. It won't just be theoretical though. We will be designing a user interface (UI) of a game menu and we will see and edit our first Java code as well.

      In addition, we will see how we can run our apps in either an Android emulator on our PC/Mac or on a real Android device if we have one.

      Some of what we will cover in this chapter will be the tip of the iceberg. That is, there is a lot more below the surface to some of the topics we discuss than would be appropriate for the second chapter of a learning Java book. Sometimes, we might need to take a bit of information on faith.

      This will then enable us to actually design and run our very own Android app by the end of this chapter. Then we can start learning Java for real at the beginning of the next chapter.

      If this chapter seems a little tough, then don't worry; keep going because each subsequent chapter lifts the lid a bit more from some of the less clear topics.

      For this chapter and the next two, we will be building a math game. We will start simply and by the end of Chapter 4, Discovering Loops and Methods, we will scale to game features that use significant Java skills.

      In this chapter, we will:

      Start our first game project

      Explore Android Studio

      Use the Android Studio visual designer to make our game UI

      Learn about structuring our code for Android

      Take our first look at some Java code

      Build and install our game on an emulator and a real device

      Our first game project

      Now we will get straight down to actually doing something with Android Studio. Run Android Studio by double-clicking on the Android Studio icon either on your desktop's start menu or in the folder where you installed it.

      Note

      If you get any errors in a dialog box mentioning Privilege elevation, then try running Android Studio with administrator privileges. To do this, find the Android Studio icon by clicking on the Windows Start button and searching for Android Studio. Now right-click on the icon and click on Run as administrator. Do this every time you run Android Studio.

      Preparing Android Studio

      So with Android Studio and Java installed, we just need to add the latest versions of the Android API that we will use to make our first game. Here is what to do to install the API:

      From the menu bar at the top of the Android Studio UI, navigate to Tools | Android | SDK Manager. Scroll down in the Android SDK Manager window and select the checkbox for Android 4.4.2 (API 19).

      Note

      Note that because Android is evolving so quickly, by the time you read this chapter, there might be APIs newer than 19—20, 21, and so on. If this is the case for you, select the newer (higher numbered) API instead.

      Preparing Android Studio

      Click on Install Packages.

      On the next screen, click on the Accept license checkbox and then click on the Install button. Android Studio will download and install the appropriate packages.

      What we just did was setting up Android Studio to make available the latest, prewritten code called an API that we will interact with throughout the book.

      Building the project

      Click on New Project... as indicated in the following screenshot:

      Building the project

      The Create New Project configuration window will appear. Fill in the Application name field with Math Game Chapter 2 and Company Domain with packtpub.com (or you could use your own company website name here), as shown in the following screenshot:

      Building the project

      Now click on the Next button. On the next screen, check that the Phone and Tablet checkbox has a tick in it. Now we have to choose the earliest version of Android we want to build our app for. Go ahead and play with a few options in the drop-down selector. You will see that the earlier the version we select, the greater is the percentage of devices our app can support. However, the trade-off here is that the earlier the version we select, the fewer are the cutting-edge Android features available in our apps. A good balance is to select API 8: Android 2.2 (Froyo). Go ahead and do that now as shown in the next screenshot:

      Building the project

      Click on Next. Now select Blank Activity as shown in the next screenshot and click on Next again:

      Building the project

      On the next screen, simply change Activity Name to MainActivity and click on Finish.

      Tip

      By default, Android Studio shows a Tip of the day dialog every time it starts. Some of the tips might not make sense while you are still learning Java but many of them are really useful and reveal great shortcuts and other time savers. It is well worth taking a few seconds to read them when they show up. As already discussed, Android Studio is built from IntelliJ IDEA, and you can find a complete list of keyboard shortcuts at http://www.jetbrains.com/idea/webhelp/keyboard-shortcuts-you-cannot-miss.html.

      ClearTip of the day by clicking on Close.

      If you are completely new to programming, then the code, options, and files might seem a bit daunting. Don't worry; stick to them as we don't need to concern ourselves with most of them in order to learn Java. When the time does come to interact with the finer details, we will do things one step at a time.

      It might be hard to believe that at this stage, but we have just created our first working app. We could build and run it on an Android device, and soon we will.

      Let's take a deeper look at Android Studio before we progress with our game.

      Exploring Android Studio

      Android Studio is a very deep tool, but it is only necessary to learn one part at a time in order to get started. What might be useful for us is naming a few parts of the UI so that we can refer to them easily as we progress through the book.

      Take a look at this numbered diagram and a quick explanation of some of the key parts of Android Studio. If you can, try and memorize the parts to make future discussions of them easier for you.

      Exploring Android Studio

      Here is a handy table that you can quickly refer to and remember which part of Android Studio we are referring to. What follows is a more detailed explanation of each area.

      Project Explorer (1): This is shown as 1 in the screenshot and is a bit like Windows Explorer. It shows us all the files and folders that have been generated for our project. We will do a number of things from here as the book continues. Actually, if you delve into the files and folders that Android Studio creates, the Project Explorer is not an exact mapping. It is slightly simplified and highlighted to make managing and exploring our project easier.

      The Editor (2): As the name suggests, we will edit our Java code files here in the editor. However, as we will soon see, the Editor window changes depending on the type of file we are editing. We will also be viewing and editing UI designs here.

      Menu bar (3): Like most programs, the Menu bar gives us access to the full functionality of Android Studio.

      Tool bar (4): This contains lots of really useful one-click options to do things such as deploying and debugging our games. Hover the mouse cursor over an icon to get a pop-up tip and gain greater insight into each toolbar icon.

      Navigation bar (5): Like a file path, this shows exactly where the file that is currently in the editor is located within the project.

      Important tool windows (6): These are a number of tabs that can be popped up and popped down again by clicking on them. If you like, try some of them now to see how they work.

      Let's talk a bit more about the parts of the Android Studio UI and how the editor window can transform itself into a visual UI designer. After that, when we are familiar enough, we will look at building a simple menu screen for our math game.

      Using the Android Studio visual designer

      The Android Studio editor window is a very dynamic area. It presents different file types in the most useful way possible. A little earlier, when we created our project, it also made a basic UI for us. UIs in Android can be built-in Java code or, as we will see, in a visual designer without the need for a single line of Java. However, as we will investigate after we have built the UI of our game menu, to get the UI to do anything useful, we need to interact with it. This interaction is always done with Java code. The visual designer also generates the UI code for us. We will take a very quick look at that too.

      As the book progresses, we will mainly shy away from Android UI development, as that is a staple of more non-game apps. We will instead spend more time looking at directly drawing pixels and images to make our games. Nonetheless, the regular Android UI has its uses, and the Android Studio visual designer is the quickest way to get started.

      Let's have a look at that now:

      In the Android Studio Project Explorer, double-click on the layout folder to reveal the activity_main.xml file within it. This should be easy to see unless you have collapsed the directories. If you can't see the layout folder, navigate to it using the Project Explorer. It can be found at Math Game Chapter2/src/main/res/layout via the Android Studio Project Explorer, as shown in the following screenshot:

      Using the Android Studio visual designer

      Now double-click on activity_main.xml to open it in the editor window. After a brief loading time, you will see something very similar to the next screenshot. The following screenshot shows the entire contents of what previously contained just our code. As you can see, what was just a text window now has multiple parts. Let's take a closer look at this screenshot:

      Using the Android Studio visual designer

      In the preceding screenshot labeled (1), called Palette, you can choose from the available Android UI elements and simply click and drag them onto your UI design. Area (2) is the visual view of the UI you are building, where you will click and drag elements from the palette. To the right of the visual UI view, you will see the Component Tree area (3). The component tree allows you to examine the structure of the complex UI and select specific elements more easily. Under this tree is the Properties panel (4). Here you can adjust the properties of the currently selected UI

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