Learning Java by Building Android Games - Second Edition

Book Image

Learning Java by Building Android Games - Second Edition

By : John Horton

Book Image

Learning Java by Building Android Games - Second Edition

By: John Horton

Overview of this book

Android is one of the most popular mobile operating systems presently. It uses the most popular programming language, Java, as the primary language for building apps of all types. However, this book is unlike other Android books in that it doesn’t assume that you already have Java proficiency. This new and expanded second edition of Learning Java by Building Android Games shows you how to start building Android games from scratch. The difficulty level will grow steadily as you explore key Java topics, such as variables, loops, methods, object oriented programming, and design patterns, including code and examples that are written for Java 9 and Android P. At each stage, you will put what you’ve learned into practice by developing a game. You will build games such as Minesweeper, Retro Pong, Bullet Hell, and Classic Snake and Scrolling Shooter games. In the later chapters, you will create a time-trial, open-world platform game. By the end of the book, you will not only have grasped Java and Android but will also have developed six cool games for the Android platform.

Learning Java by Building Android Games Second Edition

Learning Java by Building Android Games Second Edition

Contributors

Preface

Free Chapter

Java, Android and Game Development

Java, Android and Game Development

What's new in the second edition?

Why Java, Android and Games?

The games you will build

How Java and Android work

Setting up Android Studio

Starting the first project: Sub' Hunter

Android Studio and our project – A very brief guided tour

Locking the game to full-screen and landscape orientation

Deploying the game so far

Java: First Contact

Java: First Contact

Planning the Sub' Hunter game

Introduction to Java methods

Structuring Sub' Hunter with methods

Introduction to Object Oriented Programming

Using Java packages

Linking up our methods

Variables, Operators and Expressions

Variables, Operators and Expressions

Handling syntax and jargon

How to use variables

Making variables useful with operators

Declaring and Initializing the Sub' Hunter Variables

Errors, warnings, and bugs

Testing the game

Structuring Code with Java Methods

Structuring Code with Java Methods

Scope: Methods and Variables

Generating random numbers to deploy a sub

Testing the game

The Android Canvas Class – Drawing to the Screen

The Android Canvas Class – Drawing to the Screen

Understanding the Canvas class

Using the Canvas class

Canvas Demo app

Android Coordinate system

Drawing the Sub' Hunter graphics and text

Repeating Blocks of Code with Loops

Repeating Blocks of Code with Loops

Decisions, decisions

Keeping things tidy

Using for loops to draw the Sub' Hunter grid

Making Decisions with Java If, Else and Switch

Making Decisions with Java If, Else and Switch

If they come over the bridge shoot them

Combining different control flow blocks

Making sense of the screen touches

Running the game

Object-Oriented Programming

Object-Oriented Programming

Basic Object-Oriented Programming

Looking at the code for a class

Basic classes mini-app

Remember that encapsulation thing?

Encapsulation and static methods mini-app

OOP and inheritance

Inheritance mini-app

Starting the Pong game

The Game Engine, Threads, and The Game Loop

The Game Engine, Threads, and The Game Loop

Coding the PongActivity class

Coding the PongGame class

Coding the PongGame class

Implementing the game loop with a thread

Running the game

Coding the Bat and Ball

Coding the Bat and Ball

Coding the Bat input handling

Running the game

Collisions, Sound Effects and Supporting Different Versions of Android

Collisions, Sound Effects and Supporting Different Versions of Android

Handling collisions

Handling different versions of Android

The Soundpool class

Generating sound effects

Adding sound to the Pong game

Coding the collision detection and playing sounds

Playing the game

Handling Lots of Data with Arrays

Handling Lots of Data with Arrays

Planning the project

Starting the project

Reusing the Pong engine

Coding the Bullet class

Simple array example mini-app

Getting dynamic with arrays

Entering the nth dimension with Arrays

Spawning an array of bullets

Bitmap Graphics and Measuring Time

Bitmap Graphics and Measuring Time

The Bob (player's) class

Running the game

The Stack, the Heap, and the Garbage Collector

The Stack, the Heap, and the Garbage Collector

Managing and understanding memory

Introduction to the Snake game

Getting started with the Snake game

Coding the game engine

Running the game

Android Localization -Hola!

Android Localization -Hola!

Making the snake game Spanish, English and German

Run the game in German or Spanish

Collections, Generics and Enumerations

Collections, Generics and Enumerations

Adding the graphics

Coding the apple

Using the apple

Using Arrays in the snake game

Arrays and ArrayLists are polymorphic

Manipulating Bitmaps and Coding the Snake class

Manipulating Bitmaps and Coding the Snake class

Rotating Bitmaps

Add the sound to the project

Coding the Snake class

Running the completed game

Introduction to Design Patterns and much more!

Introduction to Design Patterns and much more!

Introducing the Scrolling Shooter project

Game programming patterns and the structure of the Scrolling Shooter project

Starting the project

Controlling the game with a GameState class

Giving partial access to a class using an interface

Building a sound engine

Testing the game so far

Building a HUD class to display control buttons and text

Building a Renderer class to handle the drawing

Using the HUD and Renderer classes

Running the game

Listening with the Observer Pattern, Multitouch and Building a Particle System

Listening with the Observer Pattern, Multitouch and Building a Particle System

The Observer pattern

Coding the Observer pattern in Scrolling Shooter

Coding a Multitouch UI controller and making it a listener

Running the game

Implementing a particle system explosion

Building a physics engine to get things moving

Running the game

More Patterns, a Scrolling Background and Building the Player's ship

More Patterns, a Scrolling Background and Building the Player's ship

Meet the game objects

The Entity-Component pattern

The Simple Factory pattern

The object specifications

Coding the component Interfaces

Coding the player's and the background's empty component classes

Every GameObject has a transform

Every object is a GameObject

Completing the player's and the background's components

Building the GameObjectFactory

Coding the Level class

Putting everything together

Running the game

Completing the Scrolling Shooter Game

Completing the Scrolling Shooter Game

Adding the alien's components

Spawning the Aliens

Running the game

Detecting collisions

Running the completed game

Exploring More Patterns and Planning the Platformer Project

Exploring More Patterns and Planning the Platformer Project

Platform Game: Bob Was in A Hurry

How we will build the platformer

Getting started with Bob was in a hurry

Specifying all the game objects with GameObjectSpec classes

Coding the component interfaces

Coding the other interfaces

The Singleton Pattern, Java HashMap, Storing Bitmaps Efficiently and Designing Levels

The Singleton Pattern, Java HashMap, Storing Bitmaps Efficiently and Designing Levels

The Singleton pattern

More Java Collections – Meet Java Hashmap

The memory problem and the BitmapStore

Coding the basic transform

Coding the inanimate and decorative components

Create the levels

Coding a stripped down GameObjectFactory

Coding a slightly commented-out game object

Coding the GameState

Code the SoundEngine

Coding the physics engine (without collision)

Coding a Renderer

Coding the camera

Coding the UIController class

Code the Activity

Code the GameEngine

Coding the LevelManager class

Running the game

Sprite-sheet animations, Controllable Player and Parallax Scrolling Backgrounds

Sprite-sheet animations, Controllable Player and Parallax Scrolling Backgrounds

Animating sprite-sheets

Coding the Animator

Coding the player's components and transform

Coding a parallax background

Updating the levelManager, GameObjectFactory and GameObject

Running the game

Intelligent Platforms and Advanced Collision Detection

Intelligent Platforms and Advanced Collision Detection

Coding the moving platform component class

Update LevelManager and GameObjectFactory

Running the game

Coding the detectCollisions method: Part 1

Coding the detectCollisions method: Part 2

Running the game

What next?

Using the assets from the book

Future learning

My other channels

Index

Customer Reviews

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Coding the Hud

The HUD in this game is no more complex than the previous game. We will define some Rect instances to draw the controls on the screen, we will rely on GameState to provide the time and fastest times for each level and we will make the button Rect ArrayList available so that GameEngine can pass then them to our two classes that require them to handle the player's input.

Get started by adding a new class called HUD and add the following members and constructor method.

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.Rect;

import java.util.ArrayList;

class HUD {
    private Bitmap mMenuBitmap;

    private int mTextFormatting;
    private int mScreenHeight;
    private int mScreenWidth;
    final float ONE_THIRD = .33f;
    final float TWO_THIRDS = .66f;

    private ArrayList...