Develop Reference

FATAL EXCEPTION: Thread Android

I am trying to draw bullets on the screen when the player presses, but
after a few bullets I get the following error: FATAL EXCEPTION: Thread-2
Here is the classes of the bullet and of the gameView
public class Bullet {
private int x;
private int y;
private int speed;
private Bitmap bitmap;
public Bullet(Context context,int PositionX,int PositionY) {
Log.v("i am in bullet"," come on!!!");
speed = 10;
x = PositionX;
y = PositionY;
bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.flash);
}
public void update() {
//Log.v("i am in update bullet"," come on!!!");
//animating the star horizontally right side
//by increasing x coordinate with player speed
x += 20;
}
public Bitmap getBitmap(){return bitmap;}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
returns
public class GameView extends SurfaceView implements Runnable {
private long fps;
private long timeThisFrame;
volatile boolean playing;
private Thread gameThread = null;
private Player player;
//a screenX holder
int screenX;
int i=0;
//context to be used in onTouchEvent to cause the activity transition from GameAvtivity to MainActivity.
Context context;
//the score holder
int score;
//the high Scores Holder
int highScore[] = new int[4];
//Shared Prefernces to store the High Scores
SharedPreferences sharedPreferences;
//to count the number of Misses
int countMisses;
//indicator that the enemy has just entered the game screen
boolean flag ;
//an indicator if the game is Over
private boolean isGameOver ;
private Paint paint;
private Canvas canvas;
private SurfaceHolder surfaceHolder;
private Enemy enemies;
//created a reference of the class Friend
private Friend friend;
//private Bullet bullet;
private ArrayList<Star> stars = new
ArrayList<Star>();
private ArrayList<Bullet> bullet = new
ArrayList<Bullet>();
//defining a boom object to display blast
private Boom boom;
//the mediaplayer objects to configure the background music
static MediaPlayer gameOnsound;
final MediaPlayer killedEnemysound;
final MediaPlayer gameOversound;
public GameView(Context context, int screenX, int screenY) {
super(context);
player = new Player(context, screenX, screenY);
surfaceHolder = getHolder();
paint = new Paint();
//initializing context
this.context = context;
int starNums = 20;
for (int i = 0; i < starNums; i++) {
Star s = new Star(context,screenX, screenY);
stars.add(s);
}
enemies = new Enemy(context,screenX,screenY);
//initializing boom object
boom = new Boom(context);
//initializing the Friend class object
friend = new Friend(context, screenX, screenY);
//setting the score to 0 initially
score = 0;
//setting the countMisses to 0 initially
countMisses = 0;
this.screenX = screenX;
isGameOver = false;
//initializing shared Preferences
sharedPreferences = context.getSharedPreferences("SHAR_PREF_NAME",Context.MODE_PRIVATE);
//initializing the array high scores with the previous values
highScore[0] = sharedPreferences.getInt("score1",0);
highScore[1] = sharedPreferences.getInt("score2",0);
highScore[2] = sharedPreferences.getInt("score3",0);
highScore[3] = sharedPreferences.getInt("score4",0);
//initializing the media players for the game sounds
gameOnsound = MediaPlayer.create(context,R.raw.gameon);
killedEnemysound = MediaPlayer.create(context,R.raw.killedenemy);
gameOversound = MediaPlayer.create(context,R.raw.gameover);
//starting the music to be played across the game
gameOnsound.start();
}
#Override
public void run() {
while (playing) {
long startFrameTime = System.currentTimeMillis();
synchronized (surfaceHolder) {
update();
draw();
control();
}
timeThisFrame = System.currentTimeMillis() - startFrameTime;
if (timeThisFrame >= 1) {
fps = 1000 / timeThisFrame;
}
}
}
private void update() {
//incrementing score as time passes
score++;
player.update();
//setting boom outside the screen
boom.setX(-250);
boom.setY(-250);
for (Star s : stars) {
s.update(player.getSpeed());
}
for (Bullet b : bullet) {
b.update();
}
//setting the flag true when the enemy just enters the screen
if(enemies.getX()==screenX){
flag = true;
}
enemies.update(player.getSpeed(),getFps());
}
private void draw() {
if (surfaceHolder.getSurface().isValid()) {
canvas = surfaceHolder.lockCanvas();
canvas.drawColor(Color.argb(500,135,206,250));
paint.setColor(Color.WHITE);
paint.setTextSize(20);
for (Star s : stars) {
canvas.drawBitmap(
s.getBitmap(),
s.getX(),
s.getY(),
paint);
}
for (Bullet b : bullet) {
canvas.drawBitmap(
b.getBitmap(),
b.getX(),
b.getY(),
paint);
}
canvas.drawBitmap(
player.getBitmap(),
player.getX(),
player.getY(),
paint);
canvas.drawBitmap( enemies.getBitmap(), enemies.getframeToDraw(), enemies.getwhereToDraw(), null);
//drawing the score on the game screen
paint.setTextSize(30);
canvas.drawText("Score:"+score,100,50,paint);
//drawing boom image
canvas.drawBitmap(
boom.getBitmap(),
boom.getX(),
boom.getY(),
paint
);
//draw game Over when the game is over
if(isGameOver){
paint.setTextSize(150);
paint.setTextAlign(Paint.Align.CENTER);
int yPos=(int) ((canvas.getHeight() / 2) - ((paint.descent() + paint.ascent()) / 2));
canvas.drawText("Game Over",canvas.getWidth()/2,yPos,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) {
gameThread.interrupt();
}
}
public void resume() {
playing = true;
gameThread = new Thread(this);
gameThread.start();
}
//stop the music on exit
public static void stopMusic(){
gameOnsound.stop();
}
#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;
}
//if touch the player
if (player.getDetectCollision().contains((int)motionEvent.getX(), (int)motionEvent.getY())) {
Bullet b = new Bullet(context,player.getX()+player.getDetectCollision().width()
,player.getY()-(player.getDetectCollision().height()/2));
bullet.add(b);
Log.d("test", "touch not inside myEditText");
}
//if the game's over, tappin on game Over screen sends you to MainActivity
if(isGameOver){
if(motionEvent.getAction()==MotionEvent.ACTION_DOWN){
context.startActivity(new Intent(context,MainActivity.class));
}
}
return true;
}
public long getFps(){
return fps;
}
}

Android app crashes upon attempt to switch to a different Activity

I am running into an issue in my app. When my game ends (when life == 0) I am attempting to switch to a game over screen by using a different activity. When the game ends, the app simply crashes. I have included the XML for the activity I am trying to switch from as well as indicating where the app crashes. If anyone could help out, that would be great! Thanks.
activity_game.XML:
SurfaceView I am trying to switch from once game ends:
public class SVGameView extends SurfaceView implements Runnable {
private SurfaceHolder holder;
Thread thread = null;
volatile boolean running = false;
static final long FPS = 30;
private Sprite sprite;
private long lastClick;
private Bitmap ball, gameOver;
//private int x = 200, y = 200;
private int scorePosX = 100;
private int scorePosY = 100;
private int countScore = 0;
private int life = 1;
public SVGameView(Context context) {
super(context);
thread = new Thread(this);
holder = getHolder();
holder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
running = false;
while (retry) {
try {
thread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
running = true;
thread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
}
});
ball = BitmapFactory.decodeResource(getResources(), R.drawable.ball2);
gameOver = BitmapFactory.decodeResource(getResources(),R.drawable.endscreen);
sprite = new Sprite(this, ball);
}
#Override
public void run() {
long ticksPS = 1000 / FPS;
long startTime;
long sleepTime;
while (running) {
Canvas c = null;
startTime = System.currentTimeMillis();
try {
c = getHolder().lockCanvas();
synchronized (getHolder()) {
update();
draw(c);
}
} finally {
if (c != null) {
getHolder().unlockCanvasAndPost(c);
}
}
sleepTime = ticksPS-(System.currentTimeMillis() - startTime);
try {
if (sleepTime > 0)
thread.sleep(sleepTime);
else
thread.sleep(10);
} catch (Exception e) {}
}
}
private void update(){
sprite.update();
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);
Paint paint = new Paint();
canvas.drawPaint(paint);
paint.setColor(Color.WHITE);
paint.setTextSize(48);
canvas.drawText("Score: " + countScore, scorePosX, scorePosY, paint);
canvas.drawText("Lives: " + life, 500, 100, paint);
sprite.onDraw(canvas);
//Crashes here
if(life == 0) {
getContext().startActivity(new Intent(getContext(), SVGameOver.class));
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
if(System.currentTimeMillis()-lastClick > 300){
lastClick = System.currentTimeMillis();
}
synchronized (getHolder()){
if(sprite.isHit(event.getX(), event.getY())){
countScore += 1;
sprite.increase();
}else{
life --;
}
}
return super.onTouchEvent(event);
}
}
Activity I am trying to reach once the game ends:
public class SVGameOver extends Activity {
private Bitmap gameOverScreen;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
gameOverScreen = BitmapFactory.decodeResource(getResources(), R.drawable.endscreen);
}
protected void onDraw(Canvas canvas){
canvas.drawBitmap(gameOverScreen, 0,0,null);
}
}

I think logcat is asking you the right question: "have you declared this activity in your AndroidManifest.xml" ?
If you think you did it, It's highly probable you did it in a wrong way, most of the times that you think you added an Activity to the manifest but you are receiving this kind of crash, 99,9% of the time you declared it with a wrong namespace

Declare SVGameOver activity in your AndroidManifest.xml:
<activity
android:name="com.example.welcome.assignment2.SVGameOver">
...
</activity>

How to insert a .png background in SurfaceView?

I'm current creating a game and i've made 3 main classes - GameView (which extends surfaceview), GameViewThread (which is a thread used for surfaceview) and a MainActivity.
I want to enter a background image in SurfaceView, but have not been able to figure out how to do so.
Using setBackground() in the onDraw method of GameView doesn't work as well.
I would greatly appreciate any help you guys can provide me with.
Here is my GameView class:
public class GameView extends SurfaceView implements SurfaceHolder.Callback {
private Bitmap bmp1;
private SurfaceHolder holder;
private GameLoopThread gameLoopThread;
private Sprite sprite;
private float sensorX = 0;
private Platform platform[] = new Platform[7];
private Bonus GravUp[] = new Bonus[3];
private Bonus GravDown[] = new Bonus[3];
private Bitmap bmp2;
private Bitmap bmp3;
private boolean collision;
private int a;
private int b;
private int c1;
private double c2;
int agility = 50;
private Bitmap bmp4;
public double getsensorX() {
return sensorX;
}
public double setsensorX(float s) {
return sensorX = s;
}
synchronized public int getSpriteY() {
return sprite.y;
}
synchronized public int getSpriteX() {
return sprite.x;
}
synchronized public int getSpriteHeight() {
return sprite.height;
}
synchronized public int getSpriteWidth() {
return sprite.width;
}
public GameView(Context context) {
super(context);
gameLoopThread = new GameLoopThread(this);
holder = getHolder();
holder.addCallback(this);
bmp1 = BitmapFactory.decodeResource(getResources(), R.drawable.russel);
sprite = new Sprite(this);
sprite.getBMP(bmp1);
bmp2 = BitmapFactory.decodeResource(getResources(), R.drawable.brick);
bmp3 = BitmapFactory.decodeResource(getResources(), R.drawable.gravup);
bmp4 = BitmapFactory.decodeResource(getResources(), R.drawable.gravdown);
for (int i = 0; i < GravUp.length; i++) {
GravUp[i] = new Bonus(this, bmp3);
}
for (int i = 0; i < GravDown.length; i++) {
GravDown[i] = new Bonus(this, bmp4);
}
for (int i = 0; i < platform.length; i++) {
Random r = new Random();
platform[i] = new Platform(this, bmp2, 850 + 200 * i,
400 - r.nextInt(250));
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
gameLoopThread.setRunning(false);
while (retry) {
try {
gameLoopThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
gameLoopThread.setRunning(true);
gameLoopThread.start();
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.YELLOW);
sprite.Draw(canvas);
for (int i = 0; i < platform.length; i++) {
platform[i].Draw(canvas);
}
for (int i = 0; i < GravUp.length; i++) {
GravUp[i].Draw(canvas);
}
for (int i = 0; i < GravDown.length; i++) {
GravDown[i].Draw(canvas);
}
}
My MainActivity Class:
public class MainActivity extends Activity {
GameView gameView;
FrameLayout game;
RelativeLayout GameButtons;
Button butOne;
Button butTwo;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
gameView = new GameView(this);
game = new FrameLayout(this);
GameButtons = new RelativeLayout(this);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.MATCH_PARENT,
RelativeLayout.LayoutParams.MATCH_PARENT);
GameButtons.setLayoutParams(params);
game.addView(gameView);
game.addView(GameButtons);
setContentView(game);
}
}
How can I use an image I have saved in res/drawable-hdpi folder as the background to my game?
Should I use the command in GameView or MainActivity?
Do let me know if you need more information in order to help me out!
Thank you

Animations in Android

I'm new in Android and I want to do some animations. I'm trying to make my sprite sheet move automatically. But there is a problem with screen rendering. It leaves a trail while it is moving.Click here to see the screen shot
This is my code:
public class SampleAnimationActivity extends Activity {
/** Called when the activity is first created. */
Screen screen;
MapAnimation mapAnimation;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
screen = new Screen(this);
setContentView(screen);
}
#Override
protected void onDestroy() {
super.onDestroy();
}
#Override
protected void onPause() {
super.onPause();
}
#Override
protected void onResume() {
super.onResume();
}
public class Screen extends SurfaceView implements Callback{
private SurfaceHolder holder;
private MySurfaceViewThread mySurfaceViewThread;
private boolean isSurfaceCreated;
private Bitmap character, tiles;
public Screen(Context context) {
super(context);
initialize();
}
public void initialize(){
//Create a new SurfaceHolder and assign this class as its callback...
holder = getHolder();
holder.addCallback(this);
isSurfaceCreated = false;
character = BitmapFactory.decodeResource(getResources(),R.drawable.penguin_sprite);
tiles = BitmapFactory.decodeResource(getResources(), R.drawable.tile_sprites);
resume();
}
public void resume(){
//Create and start the graphics update thread.
if(mySurfaceViewThread == null){
mySurfaceViewThread = new MySurfaceViewThread();
if(isSurfaceCreated == true){
mySurfaceViewThread.start();
}
}
}
public void pause(){
//Kill the graphics update thread
if(mySurfaceViewThread != null){
mySurfaceViewThread.pause();
mySurfaceViewThread = null;
}
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
isSurfaceCreated = true;
if(mySurfaceViewThread != null){
mySurfaceViewThread.start();
}
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
isSurfaceCreated = false;
pause();
}
public class MySurfaceViewThread extends Thread{
private boolean isPaused;
private boolean characterLoaded, characterDrawn;
private SurfaceHolder surfaceHolder;
public MySurfaceViewThread(){
super();
isPaused = false;
characterLoaded = false;
surfaceHolder = holder;
characterDrawn = false;
}
public void run(){
//Repeat the drawing loop until the thread is stopped
while(!isPaused){
if(!surfaceHolder.getSurface().isValid()){
continue;
}
if(characterLoaded == false){
mapAnimation = new MapAnimation(screen, character);
characterLoaded = true;
}
Canvas canvas = surfaceHolder.lockCanvas();
mapAnimation.onDraw(canvas);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
public void pause(){
}
public void onDraw(){
}
}
}
}
public class MapAnimation {
private Screen screen;
private Bitmap character;
private int width, height, xPosition, yPosition, xSpeed, ySpeed;
public MapAnimation(Screen screen, Bitmap character) {
this.screen = screen;
this.character = character;
this.width = character.getWidth();
this.height = character.getHeight();
xPosition = 0;
yPosition = 0;
xSpeed = 5;
ySpeed = 5;
}
public void updateCharacter(){
if(xPosition > screen.getWidth() - width - xSpeed){
xSpeed = 0;
ySpeed = 5;
}
if(yPosition > screen.getHeight() - height - ySpeed){
xSpeed = -5;
ySpeed = 0;
}
if(xPosition + xSpeed < 0){
xPosition=0;
xSpeed = 0;
ySpeed = -5;
}
if(yPosition+ySpeed < 0){
yPosition = 0;
xSpeed = 5;
ySpeed = 0;
}
xPosition += xSpeed;
yPosition += ySpeed;
}
public void onDraw(Canvas canvas){
updateCharacter();
Rect src = new Rect(0, 0,135,225);
Rect dst = new Rect(xPosition, yPosition, xPosition+width, yPosition+height);
canvas.drawBitmap(character, src, dst, null);
}
}
Your help will be deeply appreciated :)

I already solved my problem, I just need to add "drawColor(color.BLACk);" before calling mapAnimation.onDraw() method.

Android animation acting strange with .sleep() onTouchEvent

I currently have (among others) these classes:
public class Main extends Activity {
Panel p;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
p = new Panel(this);
setContentView(p);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
p.onTouchEvent(event);
// Make your UI thread sleep.
try {
Thread.sleep(30);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return true;
}
and
public class Panel extends SurfaceView implements SurfaceHolder.Callback {
private ViewThread mThread;
private ArrayList<GraphicsElement> mElements = new ArrayList<GraphicsElement>();
public static int panelHeight;
public static int panelWidth;
private int numberOfElements = 0;
private Paint mPaint;
public Panel(Context context) {
super(context);
getHolder().addCallback(this);
mThread = new ViewThread(this);
mPaint = new Paint();
mPaint.setColor(Color.CYAN);
mPaint.setTextSize(20);
}
public void doDraw(long elapsed, Canvas canvas) {
canvas.drawColor(Color.parseColor("#003045"));
if (!(mElements.size() > 15)) {
synchronized (mElements) {
for (GraphicsElement element : mElements) {
element.doDraw(canvas);
}
canvas.drawText("FPS: " + Math.round(1000f / elapsed) + " Elements: " + numberOfElements, 10, 30, mPaint);
}
} else {
mElements.clear();
numberOfElements = 0;
}
}
public void animate(long elapsedTime) {
synchronized (mElements) {
for (GraphicsElement element : mElements) {
element.animate(elapsedTime);
}
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
int action = event.getAction();
int xspeed = 0;
int yspeed = 0;
if (action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_MOVE) {
if (event.getX() > panelWidth / 2) {
xspeed = 5;
} else if (event.getX() < panelWidth / 2) {
xspeed = -5;
}
synchronized (mElements) {
for (GraphicsElement element : mElements) {
element.changeSpeed(xspeed, yspeed);
}
}
}
return true;
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
#Override
public void surfaceCreated(SurfaceHolder holder) {
if (!mThread.isAlive()) {
mThread = new ViewThread(this);
mThread.setRunning(true);
mThread.start();
}
mElements.add(new GraphicsElement(getResources(), 80, 300));
numberOfElements += 1;
}
public void surfaceDestroyed(SurfaceHolder holder) {
I also have ViewThread, just my animation thread, and GraphicsElement, which defines the moving object. My animation is going very slow(on touch), and I think it has something to do with my .sleep() method. Could anyone please help me ?
Edit: I'm using .sleep() because I don't want to flood TouchEvents.
i'm trying to get it like: Check for TouchEvent, Sleep, Check for TouchEvent, Sleep.. etc...

I've had the same issues with touch slowing things down and ended up with a similar approach to yours (sleeping the UI thread on touch events, as recommended by a Google game developer). The thing that seemed to help me was playing with the length of the sleep time. Try increasing it to 70 ms or even more and see if that helps. Most apps don't need a super high sample rate for touch input.

Firstly, you should initialize your Panel inside your onCreate() method.
Panel p = null;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
p = new Panel(this);
setContentView(p);
}
Secondly, I do not understand why you are doing a sleep in your onTouchEvent() handler. Try taking that out, and things should speed up, especially if you think that may be the cause!