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.
Table of Contents (30 chapters)
Learning Java by Building Android Games Second Edition
Contributors
Preface
Index

Coding the collision detection and playing sounds


Now we have done so much theory and preparation we can finish everything off very quickly. We will write code to detect all the various collisions, using the RectF intersects method and play sounds and call the required methods of our classes.

The bat and the ball

Add the following highlighted code inside the detectCollisions method.

private void detectCollisions(){
   // Has the bat hit the ball?
   if(RectF.intersects(mBat.getRect(), mBall.getRect())) {
         // Realistic-ish bounce
         mBall.batBounce(mBat.getRect());
         mBall.increaseVelocity();
         mScore++;
         mSP.play(mBeepID, 1, 1, 0, 0, 1);
   }

   // Has the ball hit the edge of the screen

   // Bottom

   // Top

   // Left

   // Right

}

Note

You will need to import the RectF class.

import android.graphics.RectF;

In the previous code this line returns true when the ball hits the bat and will cause the code inside to execute.

if(RectF.intersects(mBat.getRect...