I programmed an Android game via this Youtube tutorial, there you can see how the game should look like at the end.
我通过这个Youtube教程编写了一个Android游戏，在那里你可以看到游戏最后的样子。
Everything went fine until I added the Gameover Screen. When I start the emulator, the Game runs accordingly, but when I have used up all my lives and the View should change to the Gameover Screen, it only appears for 1 second and then crashes (the game exits).
一切都很顺利，直到我在屏幕上添加了游戏。当我启动仿真器时，游戏会相应地运行，但是当我用尽了所有的生命并且视图应该改变为Gameover屏幕时，它只出现了1秒，然后就崩溃了(游戏退出)。
This is what the LogCat says:
LogCat是这样说的:
04-05 06:14:22.178: E/AndroidRuntime(1201): FATAL EXCEPTION: Thread-87
04-05 06:14:22.178: E/AndroidRuntime(1201): Process: com.skies.game, PID: 1201
04-05 06:14:22.178: E/AndroidRuntime(1201): java.lang.NullPointerException
04-05 06:14:22.178: E/AndroidRuntime(1201): at com.skies.game.GameView.draw(GameView.java:79)
04-05 06:14:22.178: E/AndroidRuntime(1201): at com.skies.game.GameLoopThread.run(GameLoopThread.java:30)
Here is my GameOverActivity class
这是我的游戏过动类
package com.skies.game;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class GameOverActivity extends Activity implements OnClickListener {
private Button bReplay;
private Button bExit;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.gameoverscreen);
bReplay = (Button) findViewById(R.id.bReplay);
bExit = (Button) findViewById(R.id.bExit);
bReplay.setOnClickListener(this);
bExit.setOnClickListener(this);
initialize();
}
public void onClick(View v) {
switch (v.getId()) {
case R.id.bReplay:
Intent newGameScreen = new Intent(this, GameActivity.class);
startActivity(newGameScreen);
this.finish();
break;
case R.id.bExit:
this.finish();
break;
}
}
public int readHighscore() {
SharedPreferences pref = getSharedPreferences("GAME", 0);
return pref.getInt("HIGHSCORE", 0);
}
public void initialize() {
int score = this.getIntent().getExtras().getInt("score");
TextView tvScore = (TextView) findViewById(R.id.tvScore);
tvScore.setText("Your score is: " + Integer.toString(score));
TextView tvHighscore = (TextView) findViewById(R.id.tvHighScore);
tvHighscore.setText("Endless Game Highscore: "
+ Integer.toString(readHighscore()));
}
}
Here is my GameActivity class
这是我的游戏活动课程
package com.skies.game;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.view.Menu;
public class GameActivity extends Activity {
private GameView theGameView;
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
theGameView = new GameView(this);
setContentView(theGameView);
}
public void onGameOver()
{
compareScore();
Intent theNextIntent = new Intent (getApplicationContext(), GameOverActivity.class);
theNextIntent.putExtra("score", theGameView.getScore());
startActivity(theNextIntent);
this.finish();
}
public int readHighscore()
{
SharedPreferences pref = getSharedPreferences("GAME", 0);
return pref.getInt("HIGHSCORE", 0);
}
public void writeHighscore(int highscore)
{
SharedPreferences pref = getSharedPreferences("GAME", 0);
SharedPreferences.Editor editor = pref.edit();
editor.putInt("HIGHSCORE", highscore);
editor.commit();
}
public void compareScore()
{
if(theGameView.getScore() > readHighscore())
{
writeHighscore(theGameView.getScore());
}
}
}
and here my GameView class
这是我的GameView类
package com.skies.game;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
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.Typeface;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class GameView extends SurfaceView {
private List<Sprite> spriteList = new ArrayList<Sprite>();
private List<Integer> spriteListNum = new ArrayList<Integer>();
private SurfaceHolder surfaceHolder;
private Bitmap bmp;
private Bitmap livesPicture;
private GameLoopThread theGameLoopThread;
private boolean createSprites = true;
private long lastClick;
private int currentColorNum;
private int lives = 4;
private int score = 0;
private Paint paintRed, paintBlue, paintGreen, paintYellow;
private Paint currentColor;
private String scoreString;
private String livesString;
private float density;
private GameActivity theGameActivity= new GameActivity();
public GameView(Context context) {
super(context);
livesPicture = BitmapFactory.decodeResource(getResources(),
R.drawable.lives);
Random rnd = new Random();
theGameActivity = (GameActivity) context;
setColors();
currentColorNum = rnd.nextInt(4);
theGameLoopThread = new GameLoopThread(this);
surfaceHolder = getHolder();
surfaceHolder.addCallback(new SurfaceHolder.Callback() {
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
theGameLoopThread.setRunning(false);
while (retry) {
try {
theGameLoopThread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
public void surfaceCreated(SurfaceHolder holder) {
theGameLoopThread.setRunning(true);
theGameLoopThread.start();
}
public void surfaceChanged(SurfaceHolder holder, int format,
int width, int height) {
}
});
}
@Override
public void draw(Canvas canvas) {
canvas.drawColor(Color.DKGRAY);
if (createSprites == true) {
initialSprites();
}
for (Sprite sprite : spriteList) {
sprite.draw(canvas);
}
if (currentColorNum == 0) {
drawLines(paintBlue, canvas);
} else if (currentColorNum == 1) {
drawLines(paintRed, canvas);
} else if (currentColorNum == 2) {
drawLines(paintGreen, canvas);
} else if (currentColorNum == 3) {
drawLines(paintYellow, canvas);
}
final int fontSize = (int) (25 * density);
int yTextPos = (int) (25 * density);
Typeface font = Typeface.create("Arial", Typeface.NORMAL);
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTypeface(font);
paint.setTextSize(fontSize);
paint.setAntiAlias(true);
scoreString = String.valueOf(score);
int x = (canvas.getWidth() * 5 / 7);
final String text = "Score: " + scoreString;
canvas.drawText(text, x, yTextPos, paint);
drawLives(canvas, paint);
}
private void createSprite(int index) {
Bitmap bmp = null;
switch (index) {
case 0:
bmp = BitmapFactory.decodeResource(getResources(),
R.drawable.alienspriteblue);
break;
case 1:
bmp = BitmapFactory.decodeResource(getResources(),
R.drawable.alienspritered);
break;
case 2:
bmp = BitmapFactory.decodeResource(getResources(),
R.drawable.alienspritegreen);
break;
case 3:
bmp = BitmapFactory.decodeResource(getResources(),
R.drawable.alienspriteyellow);
break;
}
Sprite sprite = new Sprite(this, bmp);
spriteList.add(sprite);
spriteListNum.add(index);
}
private void initialSprites() {
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 3; j++)
createSprite(i);
}
createSprites = false;
}
private void rndCreateSprite() {
Random rnd = new Random(System.currentTimeMillis());
int i = rnd.nextInt(4);
createSprite(i);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (System.currentTimeMillis() - lastClick > 300) {
lastClick = System.currentTimeMillis();
synchronized (getHolder()) {
for (int i = spriteList.size() - 1; i >= 0; i--) {
Sprite sprite = spriteList.get(i);
if (sprite.isTouched(event.getX(), event.getY())) {
if (currentColorNum == spriteListNum.get(i)) {
score++;
}else{
lives--;
if(lives==0){
theGameActivity.onGameOver();
}
}
if(score==3)
lives++;
rndCreateSprite();
removeSprite(i);
changeColor();
break;
}
}
}
}
return true;
}
private void removeSprite(int index) {
spriteList.remove(index);
spriteListNum.remove(index);
}
public void setColors() {
Paint paintRed = new Paint();
paintRed.setARGB(255, 236, 27, 36);
this.paintRed = paintRed;
Paint paintBlue = new Paint();
paintBlue.setARGB(255, 36, 72, 204);
this.paintBlue = paintBlue;
Paint paintGreen = new Paint();
paintGreen.setARGB(255, 34, 177, 76);
this.paintGreen = paintGreen;
Paint paintYellow = new Paint();
paintYellow.setARGB(255, 255, 242, 0);
this.paintYellow = paintYellow;
}
public void drawLines(Paint lineColor, Canvas canvas) {
int lineWidth = (int) (10*density);
int screenHeight = getHeight();
int screenWidth = getWidth();
canvas.drawRect(0, 0, lineWidth, getHeight(), lineColor);
canvas.drawRect(0, getHeight() - lineWidth, screenWidth, screenHeight,
lineColor);
canvas.drawRect(screenWidth - lineWidth, 0, screenWidth, screenHeight,
lineColor);
currentColor = lineColor;
}
public void changeColor() {
Random rnd = new Random();
int index = rnd.nextInt(spriteListNum.size());
this.currentColorNum = spriteListNum.get(index);
switch (index) {
case 0:
currentColor = paintBlue;
break;
case 1:
currentColor = paintRed;
break;
case 2:
currentColor = paintGreen;
break;
case 3:
currentColor = paintYellow;
break;
}
}
public float getDensity() {
density = getResources().getDisplayMetrics().density;
return density;
}
private void drawLives(Canvas canvas, Paint paint){
int xHeart= (int) (15*density);
int yHeart= (int) (12*density);
if (lives == 3) {
canvas.drawBitmap(livesPicture, xHeart,
yHeart, paint);
canvas.drawBitmap(livesPicture,
xHeart + livesPicture.getWidth() + 3*density,
yHeart, paint);
canvas.drawBitmap(livesPicture, xHeart + 2
* livesPicture.getWidth() + 6*density, yHeart, paint);
}
if (lives == 2) {
canvas.drawBitmap(livesPicture, xHeart,
yHeart, paint);
canvas.drawBitmap(livesPicture,
xHeart + livesPicture.getWidth() + 3,
yHeart, paint);
}
if (lives == 1) {
canvas.drawBitmap(livesPicture, xHeart,
yHeart, paint);
}
if (lives > 3) {
livesString = String.valueOf(lives);
final String lives = livesString + "x";
canvas.drawText(lives, 35 * getDensity(), 30 * getDensity(), paint);
canvas.drawBitmap(livesPicture, 15 * getDensity() + 2
* livesPicture.getWidth() + 6, 12 * getDensity(), paint);
}
}
public int getScore() {
return this.score;
}
}
I am a beginner so I really would appreciate some help.
我是个初学者，所以我很感激你的帮助。
Edit:
编辑:
Don't create new variables inside the onDraw statement.
不要在onDraw语句中创建新的变量。
So the variables like yTextPos (int) or fontSize(int) from the draw-method should be created above with all the other global variables? Isn't this make it more confusing? Or what are the benefits?
因此，应该在上面使用所有其他全局变量创建draw-method中的yTextPos (int)或fontSize(int)之类的变量?这不是更让人困惑吗?或者好处是什么?
Also, what is line 79 in GameView.java?
另外，在GameView.java中，第79行是什么?
Do you mean
你的意思是
canvas.drawColor(Color.DKGRAY);
? This gives the background of the game the color DKGRAY. I don't have a specific image for the background yet.
吗?这给了游戏的背景颜色DKGRAY。我还没有具体的背景图像。
1 个解决方案
#1
0
I believe you should set your game running loop to false when you are in the game over state. You might need to join or something as well.
我认为你应该将游戏运行循环设置为false。你可能也需要加入。
theGameLoopThread.setRunning(true);
theGameActivity.onGameOver();
#1
0
I believe you should set your game running loop to false when you are in the game over state. You might need to join or something as well.
我认为你应该将游戏运行循环设置为false。你可能也需要加入。
theGameLoopThread.setRunning(true);
theGameActivity.onGameOver();