Android Game Development Tutorial

Hello developers, I decided to post this Android Game Development Tutorial. In this Android Game Development Tutorial we are going to create a simple 2d game using android studio. We will not be using any third party library or game engines for this android game development tutorial. So lets begin.

Android Game Development with Unity

In this tutorial we are using Android Studio, and really that is not how actual games are build in the industry. If you are really serious about Mobile Game Development, and want to become a professional, or want to start your career in Game Development Industry; then you must learn some Game Engines. And the best Game Engine to start as a Student is Unity. It is one of the most popular Game Engines. It is also free. And I have a Complete Free Course about building Android Games with Unity. Check it out Here.

But if you are just casual learner and just want to learn some basics with Android Studio, keep reading the post.

Planning the Game Story

Every game start with a story. So you need to think. Not actually 😛 because I have already decided what we will be creating.

So In our game there will be a Space Jet, and the jet has to kill the enemies by hitting them. There will also be some good guys and our Space Jet should not kill them. So basically if our Space Jet touches other character that will be destroyed. So we have to only kill the enemies.

The Game Rules

Player ship has to kill the enemies by colliding with them.
If player lets 3 enemies to go safely then the game is over.
If player kills a good guy the game is over.

We have decided the game story and the rules. Now its time to create the game. We will use Android Studio. And I am assuming all of you got Android Studio and know the basics of it.

Android Game Development Tutorial – Video Demo

Before going ahead in this tutorial you can check out this video to know what you will get at the end of this Android Game Development Tutorial part 1.

Android Game Development Tutorial – Live Demo

You can also download the apk for this part of Android Game Development Tutorial from the link given below.

Download APK

Download the Images Used

You can design and create your own character using Adobe Photoshop or other photo editing program. But if you don’t want to do it yourself you can download the images I used in this project from the link given below.

Android Game Development Images Download

Creating a New Project

Open Android Studio and create a new project.
Once the project is loaded you will get MainActivity.java and activity_main.xml
First paste all the images that you downloaded inside the drawable folder of your project.

Designing the Start Screen

Above you can see the first screen of the game. It has a nice background image with two ImageButtons. You already downloaded the images used in this screen.
As you can see it is a full screen activity. So to make your application full screen, you need to go res->values->styles.xml and modify it as the following code.

<item name="windowActionBar">false</item>

</style>

</resources>

Inside activity_main.xml write the following xml code.

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:paddingBottom="@dimen/activity_vertical_margin"

android:paddingLeft="@dimen/activity_horizontal_margin"

android:paddingRight="@dimen/activity_horizontal_margin"

android:paddingTop="@dimen/activity_vertical_margin"

android:background="@drawable/splash"

tools:context="net.simplifiedcoding.simplegame.MainActivity">

<ImageButton

android:id="@+id/buttonPlay"

android:background="@drawable/playnow"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_above="@+id/buttonScore"

android:layout_centerHorizontal="true" />

<ImageButton

android:id="@+id/buttonScore"

android:background="@drawable/highscore"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_alignParentBottom="true"

android:layout_centerHorizontal="true" />

</RelativeLayout>

When we tap the Play Now button our Game Activity will start.
Now come inside MainActivity.java and write the following code.

package net.simplifiedcoding.simplegame;

import android.content.Intent;

import android.content.pm.ActivityInfo;

import android.media.Image;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.ImageButton;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

//image button

private ImageButton buttonPlay;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

//setting the orientation to landscape

setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

//getting the button

buttonPlay = (ImageButton) findViewById(R.id.buttonPlay);

//adding a click listener

buttonPlay.setOnClickListener(this);

}

@Override

public void onClick(View v) {

//starting game activity

startActivity(new Intent(this, GameActivity.class));

}

Now you need to create a new activity named GameActivity. To create a new activity right click on the package name -> new -> activity -> empty activity

Building Game View

Now its time to build our Game View. We will be using SurfaceView for building our game view. Surfaceview provides a dedicated drawing surface.

Create a new class named GameView and write the following code.

public class GameView extends SurfaceView implements Runnable {

//boolean variable to track if the game is playing or not

volatile boolean playing;

//the game thread

private Thread gameThread = null;

//Class constructor

public GameView(Context context) {

super(context);

}

@Override

public void run() {

while (playing) {

//to update the frame

update();

//to draw the frame

draw();

//to control

control();

}

private void update() {

}

private void draw() {

}

private void control() {

try {

gameThread.sleep(17);

} catch (InterruptedException e) {

e.printStackTrace();

}

public void pause() {

//when the game is paused

//setting the variable to false

playing = false;

try {

//stopping the thread

gameThread.join();

} catch (InterruptedException e) {

}

public void resume() {

//when the game is resumed

//starting the thread again

playing = true;

gameThread = new Thread(this);

gameThread.start();

}

The above class is our GameView class. It is the actual game panel where we will play the game. The class is implementing Runnable interface. We have a volatile boolean type variable running that will track whether the game is running or not. After that we have our gameThread, it is the main game loop. Then we have the constructor to the class. We are not doing anything inside the constructor right now. Then we have the overriden method run(), here we are running a loop until the playing variable running is true. Inside the loop we are calling the following methods.
update() -> Here we will update the coordinate of our characters.
draw() -> Here we will draw the characters to the canvas.
control() -> This method will control the frames per seconds drawn. Here we are calling the delay method of Thread. And this is actually making our frame rate to aroud 60fps.
After these we have two more methods.
pause() -> To pause the game, we are stopping the gameThread here.
resume() -> To resume the game, here we are starting the gameThread.

Adding GameView to GameActivity

After tapping the play now button we are launching the GameActivity. We will set our GameView to the content of this activity. So go to GameActivity.java and modify the code as below.

I will be adding the comments only above the new code added so that you can understand what is new in this code so that you can modify your code easily.

package net.simplifiedcoding.spacefighter;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

public class GameActivity extends AppCompatActivity {

//declaring gameview

private GameView gameView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

//Initializing game view object

gameView = new GameView(this);

//adding it to contentview

setContentView(gameView);

}

//pausing the game when activity is paused

@Override

protected void onPause() {

super.onPause();

gameView.pause();

}

//running the game when activity is resumed

@Override

protected void onResume() {

super.onResume();

gameView.resume();

}

Creating Player

Create a new class Player inside your package and write the following code.

package net.simplifiedcoding.spacefighter;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

/**

* Created by Belal on 6/24/2016.

public class Player {

//Bitmap to get character from image

private Bitmap bitmap;

//coordinates

private int x;

private int y;

//motion speed of the character

private int speed = 0;

//constructor

public Player(Context context) {

x = 75;

y = 50;

speed = 1;

//Getting bitmap from drawable resource

bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.player);

}

//Method to update coordinate of character

public void update(){

//updating x coordinate

x++;

}

* These are getters you can generate it autmaticallyl

* right click on editor -> generate -> getters

* */

public Bitmap getBitmap() {

return bitmap;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

public int getSpeed() {

return speed;

}

The above code is very easy to understand. I have written comments to explain everything. So lets move ahead.

Drawing Player to GameView

To draw the player to our GameView you need to come back to the GameView.java class and modify it as below.

public class GameView extends SurfaceView implements Runnable {

volatile boolean playing;

private Thread gameThread = null;

//adding the player to this class

private Player player;

//These objects will be used for drawing

private Paint paint;

private Canvas canvas;

private SurfaceHolder surfaceHolder;

public GameView(Context context) {

super(context);

//initializing player object

player = new Player(context);

//initializing drawing objects

surfaceHolder = getHolder();

paint = new Paint();

}

@Override

public void run() {

while (playing) {

update();

draw();

control();

}

private void update() {

//updating player position

player.update();

}

private void draw() {

//checking if surface is valid

if (surfaceHolder.getSurface().isValid()) {

//locking the canvas

canvas = surfaceHolder.lockCanvas();

//drawing a background color for canvas

canvas.drawColor(Color.BLACK);

//Drawing the player

canvas.drawBitmap(

player.getBitmap(),

player.getX(),

player.getY(),

paint);

//Unlocking the canvas

surfaceHolder.unlockCanvasAndPost(canvas);

}

private void control() {

try {

gameThread.sleep(17);

} catch (InterruptedException e) {

e.printStackTrace();

}

public void pause() {

playing = false;

try {

gameThread.join();

} catch (InterruptedException e) {

}

public void resume() {

playing = true;

gameThread = new Thread(this);

gameThread.start();

}

Now try executing your application. Put your emulator in landscape mode. When you tap the play now button in the first activity you will see the moving Space Jet as shown below.

android game development tutorial — Android Game Development Tutorial

If you are getting the output as shown in the above image then Hurray!. You might have got the concept about drawing images in canvas using SurfaceView. And the movement is the magic of the coordinates. We are changing the x coordinate so it is moving horizontally ahead.

Now lets add control to our Space Jet.

Adding Controls

We will now add control to the player’s Space Jet. When the player will tap on the screen the Space Jet will boost up and after releasing the screen the Space Jet will boost down. The movement is inspired by the most popular game Flappy Bird.

To add this control we will need to detect touches of the screen. So lets begin.

Come inside GameView.java file and override the method onTouchEvent().

@Override

public boolean onTouchEvent(MotionEvent motionEvent) {

switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {

case MotionEvent.ACTION_UP:

//When the user presses on the screen

//we will do something here

break;

case MotionEvent.ACTION_DOWN:

//When the user releases the screen

//do something here

break;

}

return true;

}

Currently we need these two events only which are ACTION_UP and ACTION_DOWN. What we need to do is we need to boost up the Space Jet on ACTION_UP and boost down the Space Jet on ACTION_DOWN.

Adding Booster to Space Jet

Now we will add the booster to our Space Jet so that our player can control the Space Jet. Follow these steps to do this.

Modify the code of Player.java file as follows.

public class Player {

private Bitmap bitmap;

private int x;

private int y;

private int speed = 0;

//boolean variable to track the ship is boosting or not

private boolean boosting;

//Gravity Value to add gravity effect on the ship

private final int GRAVITY = -10;

//Controlling Y coordinate so that ship won't go outside the screen

private int maxY;

private int minY;

//Limit the bounds of the ship's speed

private final int MIN_SPEED = 1;

private final int MAX_SPEED = 20;

public Player(Context context) {

x = 75;

y = 50;

speed = 1;

bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.player);

//setting the boosting value to false initially

boosting = false;

}

//setting boosting true

public void setBoosting() {

boosting = true;

}

//setting boosting false

public void stopBoosting() {

boosting = false;

}

public void update() {

//if the ship is boosting

if (boosting) {

//speeding up the ship

speed += 2;

} else {

//slowing down if not boosting

speed -= 5;

}

//controlling the top speed

if (speed > MAX_SPEED) {

speed = MAX_SPEED;

}

//if the speed is less than min speed

//controlling it so that it won't stop completely

if (speed < MIN_SPEED) {

speed = MIN_SPEED;

}

//moving the ship down

y -= speed + GRAVITY;

//but controlling it also so that it won't go off the screen

if (y < minY) {

y = minY;

}

if (y > maxY) {

y = maxY;

}

public Bitmap getBitmap() {

return bitmap;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

public int getSpeed() {

return speed;

}

We also need to detect the size of screen so go inside GameActivity.java file and add the following code inside onCreate().

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

//Getting display object

Display display = getWindowManager().getDefaultDisplay();

//Getting the screen resolution into point object

Point size = new Point();

display.getSize(size);

//Initializing game view object

//this time we are also passing the screen size to the GameView constructor

gameView = new GameView(this, size.x, size.y);

//adding it to contentview

setContentView(gameView);

}

In the above code we are passing screen size to GameView constructor, so we also need to change the GameView constructor. So change the GameView constructor as follow.

public GameView(Context context, int screenX, int screenY) {

super(context);

//initializing player object

//this time also passing screen size to player constructor

player = new Player(context, screenX, screenY);

//initializing drawing objects

surfaceHolder = getHolder();

paint = new Paint();

}

In the above code you can see we are passing the screen size to player constructor. So again we also need to modify the Player class constructor.

public Player(Context context, int screenX, int screenY) {

x = 75;

y = 50;

speed = 1;

bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.player);

//calculating maxY

maxY = screenY - bitmap.getHeight();

//top edge's y point is 0 so min y will always be zero

minY = 0;

//setting the boosting value to false initially

boosting = false;

}

Now to complete adding the boosters come inside GameView.java file and modify the onTouchEvent() as follows.

@Override

public boolean onTouchEvent(MotionEvent motionEvent) {

switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {

case MotionEvent.ACTION_UP:

//stopping the boosting when screen is released

player.stopBoosting();

break;

case MotionEvent.ACTION_DOWN:

//boosting the space jet when screen is pressed

player.setBoosting();

break;

}

return true;

}

Now execute your application again to test the boosters. If it is working fine then you can move ahead.

Adding Background Stars

Now we will add background stars to make the background looks animating.

package net.simplifiedcoding.spacefighter;

import java.util.Random;

/**

* Created by Belal on 6/15/2016.

public class Star {

private int x;

private int y;

private int speed;

private int maxX;

private int maxY;

private int minX;

private int minY;

public Star(int screenX, int screenY) {

maxX = screenX;

maxY = screenY;

minX = 0;

minY = 0;

Random generator = new Random();

speed = generator.nextInt(10);

//generating a random coordinate

//but keeping the coordinate inside the screen size

x = generator.nextInt(maxX);

y = generator.nextInt(maxY);

}

public void update(int playerSpeed) {

//animating the star horizontally left side

//by decreasing x coordinate with player speed

x -= playerSpeed;

x -= speed;

//if the star reached the left edge of the screen

if (x < 0) {

//again starting the star from right edge

//this will give a infinite scrolling background effect

x = maxX;

Random generator = new Random();

y = generator.nextInt(maxY);

speed = generator.nextInt(15);

}

public float getStarWidth() {

//Making the star width random so that

//it will give a real look

float minX = 1.0f;

float maxX = 4.0f;

Random rand = new Random();

float finalX = rand.nextFloat() * (maxX - minX) + minX;

return finalX;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

Now come inside GameView.java and modify it as follows.

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public class GameView extends SurfaceView implements Runnable {

volatile boolean playing;

private Thread gameThread = null;

private Player player;

private Paint paint;

private Canvas canvas;

private SurfaceHolder surfaceHolder;

//Adding an stars list

private ArrayList<Star> stars = new

ArrayList<Star>();

public GameView(Context context, int screenX, int screenY) {

super(context);

player = new Player(context, screenX, screenY);

surfaceHolder = getHolder();

paint = new Paint();

//adding 100 stars you may increase the number

int starNums = 100;

for (int i = 0; i < starNums; i++) {

Star s = new Star(screenX, screenY);

stars.add(s);

}

@Override

public void run() {

while (playing) {

update();

draw();

control();

}

private void update() {

player.update();

//Updating the stars with player speed

for (Star s : stars) {

s.update(player.getSpeed());

}

private void draw() {

if (surfaceHolder.getSurface().isValid()) {

canvas = surfaceHolder.lockCanvas();

canvas.drawColor(Color.BLACK);

//setting the paint color to white to draw the stars

paint.setColor(Color.WHITE);

//drawing all stars

for (Star s : stars) {

paint.setStrokeWidth(s.getStarWidth());

canvas.drawPoint(s.getX(), s.getY(), paint);

}

canvas.drawBitmap(

player.getBitmap(),

player.getX(),

player.getY(),

paint);

surfaceHolder.unlockCanvasAndPost(canvas);

}

private void control() {

try {

gameThread.sleep(17);

} catch (InterruptedException e) {

e.printStackTrace();

}

public void pause() {

playing = false;

try {

gameThread.join();

} catch (InterruptedException e) {

}

public void resume() {

playing = true;

gameThread = new Thread(this);

gameThread.start();

}

@Override

public boolean onTouchEvent(MotionEvent motionEvent) {

switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {

case MotionEvent.ACTION_UP:

player.stopBoosting();

break;

case MotionEvent.ACTION_DOWN:

player.setBoosting();

break;

}

return true;

}

Now execute your app again. You will see a infinite scrolling background this time as shown in the following image.

Adding Enemies

So far in this Android Game Development Tutorial, we have added our player, we added an infinite scrolling background. We also added controls to our player. Now we need to add some enemies. So lets start coding the enemies.

Create a new java class named Enemy and write the following code.

package net.simplifiedcoding.spacefighter;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Rect;

import java.util.Random;

/**

* Created by Belal on 6/15/2016.

public class Enemy {

//bitmap for the enemy

//we have already pasted the bitmap in the drawable folder

private Bitmap bitmap;

//x and y coordinates

private int x;

private int y;

//enemy speed

private int speed = 1;

//min and max coordinates to keep the enemy inside the screen

private int maxX;

private int minX;

private int maxY;

private int minY;

public Enemy(Context context, int screenX, int screenY) {

//getting bitmap from drawable resource

bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.enemy);

//initializing min and max coordinates

maxX = screenX;

maxY = screenY;

minX = 0;

minY = 0;

//generating a random coordinate to add enemy

Random generator = new Random();

speed = generator.nextInt(6) + 10;

x = screenX;

y = generator.nextInt(maxY) - bitmap.getHeight();

}

public void update(int playerSpeed) {

//decreasing x coordinate so that enemy will move right to left

x -= playerSpeed;

x -= speed;

//if the enemy reaches the left edge

if (x < minX - bitmap.getWidth()) {

//adding the enemy again to the right edge

Random generator = new Random();

speed = generator.nextInt(10) + 10;

x = maxX;

y = generator.nextInt(maxY) - bitmap.getHeight();

}

//getters

public Bitmap getBitmap() {

return bitmap;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

public int getSpeed() {

return speed;

}

We need to add the enemies in the GameView now. So come inside GameView.java and modify the code as follows.

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public class GameView extends SurfaceView implements Runnable {

volatile boolean playing;

private Thread gameThread = null;

private Player player;

private Paint paint;

private Canvas canvas;

private SurfaceHolder surfaceHolder;

//Adding enemies object array

private Enemy[] enemies;

//Adding 3 enemies you may increase the size

private int enemyCount = 3;

private ArrayList<Star> stars = new

ArrayList<Star>();

public GameView(Context context, int screenX, int screenY) {

super(context);

player = new Player(context, screenX, screenY);

surfaceHolder = getHolder();

paint = new Paint();

int starNums = 100;

for (int i = 0; i < starNums; i++) {

Star s = new Star(screenX, screenY);

stars.add(s);

}

//initializing enemy object array

enemies = new Enemy[enemyCount];

for(int i=0; i<enemyCount; i++){

enemies[i] = new Enemy(context, screenX, screenY);

}

@Override

public void run() {

while (playing) {

update();

draw();

control();

}

private void update() {

player.update();

for (Star s : stars) {

s.update(player.getSpeed());

}

//updating the enemy coordinate with respect to player speed

for(int i=0; i<enemyCount; i++){

enemies[i].update(player.getSpeed());

}

private void draw() {

if (surfaceHolder.getSurface().isValid()) {

canvas = surfaceHolder.lockCanvas();

canvas.drawColor(Color.BLACK);

paint.setColor(Color.WHITE);

for (Star s : stars) {

paint.setStrokeWidth(s.getStarWidth());

canvas.drawPoint(s.getX(), s.getY(), paint);

}

canvas.drawBitmap(

player.getBitmap(),

player.getX(),

player.getY(),

paint);

//drawing the enemies

for (int i = 0; i < enemyCount; i++) {

canvas.drawBitmap(

enemies[i].getBitmap(),

enemies[i].getX(),

enemies[i].getY(),

paint

);

}

surfaceHolder.unlockCanvasAndPost(canvas);

}

private void control() {

try {

gameThread.sleep(17);

} catch (InterruptedException e) {

e.printStackTrace();

}

public void pause() {

playing = false;

try {

gameThread.join();

} catch (InterruptedException e) {

}

public void resume() {

playing = true;

gameThread = new Thread(this);

gameThread.start();

}

@Override

public boolean onTouchEvent(MotionEvent motionEvent) {

switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {

case MotionEvent.ACTION_UP:

player.stopBoosting();

break;

case MotionEvent.ACTION_DOWN:

player.setBoosting();

break;

}

return true;

}

Execute your application again and you should see the following output.

So we are almost done at this part of the Android Game Development Tutorial. Only the last thing is left. When our Space Jet touches the enemy, the enemy ship should blast. So we need a blast image and you already got it inside your drawable folder. To show the blast image we need to detect the collision between the player and enemy jet. So lets do this.

Detecting Collision

To detect collision we will use Rect object. So come inside Enemy class modify the code as follows.

public class Enemy {

private Bitmap bitmap;

private int x;

private int y;

private int speed = 1;

private int maxX;

private int minX;

private int maxY;

private int minY;

//creating a rect object

private Rect detectCollision;

public Enemy(Context context, int screenX, int screenY) {

bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.enemy);

maxX = screenX;

maxY = screenY;

minX = 0;

minY = 0;

Random generator = new Random();

speed = generator.nextInt(6) + 10;

x = screenX;

y = generator.nextInt(maxY) - bitmap.getHeight();

//initializing rect object

detectCollision = new Rect(x, y, bitmap.getWidth(), bitmap.getHeight());

}

public void update(int playerSpeed) {

x -= playerSpeed;

x -= speed;

if (x < minX - bitmap.getWidth()) {

Random generator = new Random();

speed = generator.nextInt(10) + 10;

x = maxX;

y = generator.nextInt(maxY) - bitmap.getHeight();

}

//Adding the top, left, bottom and right to the rect object

detectCollision.left = x;

detectCollision.top = y;

detectCollision.right = x + bitmap.getWidth();

detectCollision.bottom = y + bitmap.getHeight();

}

//adding a setter to x coordinate so that we can change it after collision

public void setX(int x){

this.x = x;

}

//one more getter for getting the rect object

public Rect getDetectCollision() {

return detectCollision;

}

//getters

public Bitmap getBitmap() {

return bitmap;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

public int getSpeed() {

return speed;

}

The same thing you need to do inside the Player.java file.

public class Player {

private Bitmap bitmap;

private int x;

private int y;

private int speed = 0;

private boolean boosting;

private final int GRAVITY = -10;

private int maxY;

private int minY;

private final int MIN_SPEED = 1;

private final int MAX_SPEED = 20;

private Rect detectCollision;

public Player(Context context, int screenX, int screenY) {

x = 75;

y = 50;

speed = 1;

bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.player);

maxY = screenY - bitmap.getHeight();

minY = 0;

boosting = false;

//initializing rect object

detectCollision = new Rect(x, y, bitmap.getWidth(), bitmap.getHeight());

}

public void setBoosting() {

boosting = true;

}

public void stopBoosting() {

boosting = false;

}

public void update() {

if (boosting) {

speed += 2;

} else {

speed -= 5;

}

if (speed > MAX_SPEED) {

speed = MAX_SPEED;

}

if (speed < MIN_SPEED) {

speed = MIN_SPEED;

}

y -= speed + GRAVITY;

if (y < minY) {

y = minY;

}

if (y > maxY) {

y = maxY;

}

//adding top, left, bottom and right to the rect object

detectCollision.left = x;

detectCollision.top = y;

detectCollision.right = x + bitmap.getWidth();

detectCollision.bottom = y + bitmap.getHeight();

}

//one more getter for getting the rect object

public Rect getDetectCollision() {

return detectCollision;

}

public Bitmap getBitmap() {

return bitmap;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

public int getSpeed() {

return speed;

}

Now to complete the collision detection, again to inside GameView.java file and modify the update() method as follows.

private void update() {

player.update();

for (Star s : stars) {

s.update(player.getSpeed());

}

for(int i=0; i<enemyCount; i++){

enemies[i].update(player.getSpeed());

//if collision occurrs with player

if (Rect.intersects(player.getDetectCollision(), enemies[i].getDetectCollision())) {

//moving enemy outside the left edge

enemies[i].setX(-200);

}

Again execute the app. You should see the enemies getting hidden after collision. Now after collision we will show a blast image for a fraction of second to make it look like destroying.

Adding Blast Effect

Now we are at the last phase for this part of this Android Game Development Tutorial. We need to display a blast effect after collision.

We already have a blast image inside the drawable folder. We will use that image to display for a fraction of second after the collision. So follow the following step.

Create a new java class named Boom and write the following code.

package net.simplifiedcoding.spacefighter;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

/**

* Created by Belal on 6/15/2016.

public class Boom {

//bitmap object

private Bitmap bitmap;

//coordinate variables

private int x;

private int y;

//constructor

public Boom(Context context) {

//getting boom image from drawable resource

bitmap = BitmapFactory.decodeResource

(context.getResources(), R.drawable.boom);

//setting the coordinate outside the screen

//so that it won't shown up in the screen

//it will be only visible for a fraction of second

//after collission

x = -250;

y = -250;

}

//setters for x and y to make it visible at the place of collision

public void setX(int x) {

this.x = x;

}

public void setY(int y) {

this.y = y;

}

//getters

public Bitmap getBitmap() {

return bitmap;

}

public void setBitmap(Bitmap bitmap) {

this.bitmap = bitmap;

}

public int getX() {

return x;

}

public int getY() {

return y;

}

Now again come inside GameView.java file and modify the code as follow.

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public class GameView extends SurfaceView implements Runnable {

volatile boolean playing;

private Thread gameThread = null;

private Player player;

private Paint paint;

private Canvas canvas;

private SurfaceHolder surfaceHolder;

private Enemy[] enemies;

private int enemyCount = 3;

private ArrayList<Star> stars = new

ArrayList<Star>();

//defining a boom object to display blast

private Boom boom;

public GameView(Context context, int screenX, int screenY) {

super(context);

player = new Player(context, screenX, screenY);

surfaceHolder = getHolder();

paint = new Paint();

int starNums = 100;

for (int i = 0; i < starNums; i++) {

Star s = new Star(screenX, screenY);

stars.add(s);

}

enemies = new Enemy[enemyCount];

for (int i = 0; i < enemyCount; i++) {

enemies[i] = new Enemy(context, screenX, screenY);

}

//initializing boom object

boom = new Boom(context);

}

@Override

public void run() {

while (playing) {

update();

draw();

control();

}

private void update() {

player.update();

//setting boom outside the screen

boom.setX(-250);

boom.setY(-250);

for (Star s : stars) {

s.update(player.getSpeed());

}

for (int i = 0; i < enemyCount; i++) {

enemies[i].update(player.getSpeed());

//if collision occurrs with player

if (Rect.intersects(player.getDetectCollision(), enemies[i].getDetectCollision())) {

//displaying boom at that location

boom.setX(enemies[i].getX());

boom.setY(enemies[i].getY());

enemies[i].setX(-200);

}

private void draw() {

if (surfaceHolder.getSurface().isValid()) {

canvas = surfaceHolder.lockCanvas();

canvas.drawColor(Color.BLACK);

paint.setColor(Color.WHITE);

for (Star s : stars) {

paint.setStrokeWidth(s.getStarWidth());

canvas.drawPoint(s.getX(), s.getY(), paint);

}

canvas.drawBitmap(

player.getBitmap(),

player.getX(),

player.getY(),

paint);

for (int i = 0; i < enemyCount; i++) {

canvas.drawBitmap(

enemies[i].getBitmap(),

enemies[i].getX(),

enemies[i].getY(),

paint

);

}

//drawing boom image

canvas.drawBitmap(

boom.getBitmap(),

boom.getX(),

boom.getY(),

paint

);

surfaceHolder.unlockCanvasAndPost(canvas);

}

private void control() {

try {

gameThread.sleep(17);

} catch (InterruptedException e) {

e.printStackTrace();

}

public void pause() {

playing = false;

try {

gameThread.join();

} catch (InterruptedException e) {

}

public void resume() {

playing = true;

gameThread = new Thread(this);

gameThread.start();

}

@Override

public boolean onTouchEvent(MotionEvent motionEvent) {

switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {

case MotionEvent.ACTION_UP:

player.stopBoosting();

break;

case MotionEvent.ACTION_DOWN:

player.setBoosting();

break;

}

return true;

}

Now again execute the application and you will see a blast effect on collision.

Bingo! it is working absolutely fine. You can download my source code if having any troubles or confusion. Unlock the download link to get the source code of this Android Game Development Tutorial from below.

Android Game Development Part 1 – Source Code Download

Android Game Development Tutorial – Summary

It is a really simple and small game we are creating in this Android Game Development Tutorial. This Android Game Development Tutorial is a two part series. This is the first part. In this part of this Android Game Development Tutorial we learnt:

SurfaceView implementation
Drawing Characters on Canvas using SurfaceView
Creating an Infinite Scroll Background Loop
Detecting Collision
Adding Controlls

In the next part -> Android Game Development Tutorial Part 2, we will finally complete this game by adding some text displaying high score and other game values. We will also add a game over option and some sound effects.

Android Game Development Tutorial – Final Words

So thats all for this Android Game Development Tutorial friends. This is a really long tutorial. Probably the longest one I’ve posted so far. So try it carefully. And share it among your friends if you liked this Android Game Development Tutorial. Thank You 🙂

Android Game Development Tutorial – Simple 2d Game Part 1

Android Game Development with Unity

Planning the Game Story

The Game Rules

Android Game Development Tutorial

Android Game Development Tutorial – Video Demo

Android Game Development Tutorial – Live Demo

Download the Images Used

Creating a New Project

Designing the Start Screen

Building Game View

Adding GameView to GameActivity

Creating Player

Drawing Player to GameView

Adding Controls

Adding Booster to Space Jet

Adding Background Stars

Adding Enemies

Detecting Collision

Adding Blast Effect

Android Game Development Tutorial – Summary

Android Game Development Tutorial – Final Words

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