マルチスレッド処理をするSurfaceviewにおいてonTouchEventで画像を動かしたい。

Javaでゲームのandroidアプリを作っています。ゲームプレイヤーの画像を動かしたいのですが、うまくいきません。皆様の知恵をお借りしたいです。　

Surfaceviewのクラスから、プレイヤーのクラスの変数をいじることで画像を動かそうとしているのですが、エミュレータの起動がうまくいきません。

コード全文なので長いですが、おそらくGameViewクラスのonTouchEventメソッドとサブスレッドの処理のあたりで問題が起きています。

1.この現象の解決方法を教えていただきたいです。
2.またサブスレッドとメインスレッドの処理がコンピューター内でどのようになっているのかということがあまりピンときていないので、参考になるサイト、書籍等があったら教えていただきたいです。

この2つのうち特に1.について悩んでいるので1.だけでも回答をいただけるととても嬉しいです。よろしくお願いします。

テキストエディタにandroid studioを使っています。

Java
1package com.example.dodgerun;
2
3import androidx.appcompat.app.AppCompatActivity;
4
5import android.os.Bundle;
6import android.view.View;
7
8public class MainActivity extends AppCompatActivity {
9    private GameView gameView;
10    @Override
11    protected void onCreate(Bundle savedInstanceState) {
12        super.onCreate(savedInstanceState);
13
14        gameView = new GameView(this);
15        setContentView(gameView);
16
17    }
18}

Java
1package com.example.dodgerun;
2
3//import文省略
4public class GameView extends SurfaceView implements SurfaceHolder.Callback {
5    public GameView(Context context) {
6        super(context);
7        getHolder().addCallback(this);
8    }
9
10    private static long DRAW_INTERVAL = 10;
11    //threadクラスで使うからstatic
12    private Random ran = new Random();
13    private Player player;
14    private List<Obstacle> obstacleList = new ArrayList<>();
15
16    public static final int LEFT_FLICK= 0;
17    public static final int RIGHT_FLICK = 1;
18    public static final int UP_FLICK = 2;
19    public static final int DOWN_FLICK = 3;
20
21    private float adjustX = 150.0f;
22    private float adjustY = 150.0f;
23    private float touchX;
24    private float touchY;
25    private float nowTouchX;
26    private float nowTouchY;
27
28    private final Bitmap playerBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.devil_mini);
29
30    private DrawThread drawThread;
31
32    private class DrawThread extends Thread {
33        private AtomicBoolean isFinished = new AtomicBoolean();
34        private void finish() {
35            isFinished.set(true);
36        }
37
38        @Override
39        public void run() {
40            SurfaceHolder holder = getHolder();
41            while (!isFinished.get()) {
42                if (holder.isCreating()) {
43                    continue;
44                }
45                Canvas canvas = holder.lockCanvas();
46                if (canvas == null) {
47                    continue;
48                }
49                drawGame(canvas);
50                holder.unlockCanvasAndPost(canvas);
51                                synchronized (this) {
52                    try {
53                        wait(DRAW_INTERVAL);
54                    } catch (InterruptedException e) {
55                    }
56                }
57            }
58        }
59    }
60
61    private void startDrawThread() {
62
63        drawThread = new DrawThread();
64        drawThread.start();
65    }
66
67    public boolean stopDrawThread() {
68        if (drawThread == null) {
69            return false;
70        }
71
72        drawThread.finish();
73        drawThread = null;
74        return true;
75    }
76
77    public void surfaceCreated(SurfaceHolder holder) {
78        startDrawThread();
79    }
80
81    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
82    }
83
84    public void surfaceDestroyed(SurfaceHolder holder) {
85        stopDrawThread();
86    }
87
88    protected void drawGame(Canvas canvas) {
89        canvas.drawColor(Color.WHITE);
90
91        int width = canvas.getWidth();
92        int height = canvas.getHeight();
93        if (player == null) {
94
95            player = new Player(playerBitmap, width);
96        }
97        player.draw(canvas, height);
98        //ここら辺でエラーが起きていると思います
99        Obstacle lo = launchObstacle(playerBitmap, width);
100        obstacleList.add(lo);
101        drawObstacleList(canvas, obstacleList, playerBitmap, width, height);
102        //
103
104
105    }
106
107    private Obstacle launchObstacle(Bitmap bitmap, int width) {
108        int randomX1 = ran.nextInt(bitmap.getWidth() * 2);
109        int randomX2 = ran.nextInt((width - bitmap.getWidth() * 2));
110        return new Obstacle(randomX1, randomX2);
111    }
112
113    private void drawObstacleList(Canvas canvas, List<Obstacle> obstacleList, Bitmap bitmap, int width, int height) {
114        for (int i = 0; i < obstacleList.size(); i++) {
115            Obstacle ob = obstacleList.get(i);
116            if (i % 36 == 0) {
117                ob.draw1(canvas, bitmap, width, height);
118            } else  if (i % 36 == 12 || i % 36 == 24) {
119                ob.draw2(canvas, bitmap, width, height);
120            }
121            ob.move(bitmap);
122
123        }
124    }
125    @Override
126    public boolean onTouchEvent(MotionEvent event) {
127        switch (event.getAction()) {
128            case MotionEvent.ACTION_DOWN:
129                touchX = event.getX();
130                touchY = event.getY();
131                break;
132            case MotionEvent.ACTION_UP:
133                nowTouchX = event.getX();
134                nowTouchY = event.getY();
135                check();
136                break;
137            case MotionEvent.ACTION_MOVE:
138                break;
139            case MotionEvent.ACTION_CANCEL:
140                break;
141        }
142        return true;
143    }
144    private void check(){
145        Log.d("FlickPoint", "startX:" + touchX + " endX:" + nowTouchX
146                + " startY:" + touchY + " endY:" + nowTouchY);
147        // 左フリック
148        if(touchX > nowTouchX)
149        {
150            if(touchX - nowTouchX > adjustX)
151            {
152                getFlick(LEFT_FLICK);
153                return;
154            }
155        }
156        // 右フリック
157        if(nowTouchX > touchX)
158        {
159            if(nowTouchX - touchX > adjustX)
160            {
161                getFlick(RIGHT_FLICK);
162                return;
163            }
164        }
165        // 上フリック
166        if(touchY > nowTouchY)
167        {
168            if(touchY - nowTouchY > adjustY)
169            {
170                getFlick(UP_FLICK);
171                return;
172            }
173        }
174        // 下フリック
175        if(nowTouchY > touchY)
176        {
177            if(nowTouchY - touchY > adjustY)
178            {
179                getFlick(DOWN_FLICK);
180                return;
181            }
182        }
183    }
184    public void getFlick (int direct) {
185        switch (direct){
186            case LEFT_FLICK:
187                player.setLeft_change(player.getLeft_change() - 50);
188                break;
189            case RIGHT_FLICK:
190                player.setLeft_change(player.getLeft_change() + 50);
191                break;
192        }
193    }
194
195}

Java
1package com.example.dodgerun;
2
3
4public abstract class BaseObject {
5    protected float xPosition;
6    protected float yPosition;
7}
8

Java
1package com.example.dodgerun;
2//import文省略
3public class Player extends BaseObject{
4    private Bitmap bitmap;
5    private Rect rect;
6
7    private Paint paint = new Paint ();
8
9    private float xPosition;
10    private float yPosition;
11    private int left_change;
12
13    public Player (Bitmap bitmap, int width) {
14        this.bitmap = bitmap;
15        this.left_change = (width - bitmap.getWidth()) / 2;
16        this.xPosition = rect.centerX();
17        this.yPosition = rect.centerY();
18    }
19    public void draw(Canvas canvas, int height) {
20        int top = height - bitmap.getHeight();
21        int right = this.left_change + bitmap.getWidth();
22        int bottom = top + bitmap.getHeight();
23        rect = new Rect(this.left_change, top, right, bottom);
24        canvas.drawBitmap(bitmap, rect.left, rect.top, paint);
25    }
26
27    public int getLeft_change () {
28        return this.left_change;
29    }
30    public void setLeft_change (int left_change) {
31        this.left_change = left_change;
32    }
33    public Bitmap getBitmap () {
34        return  this.bitmap;
35    }
36}
37

Java
1package com.example.dodgerun;
2
3import android.graphics.Bitmap;
4import android.graphics.Canvas;
5import android.graphics.Color;
6import android.graphics.Paint;
7
8import java.util.Random;
9
10public class Obstacle {
11    private float StrokeWidth = 20.0f;
12    Paint paint = new Paint ();
13
14    private float xPosition;
15    private float yPosition;
16
17    private final int left_widthX;
18    public Obstacle (int randomX1, int randomX2) {
19        yPosition = 0;
20        xPosition = randomX1;
21        left_widthX = randomX2;
22    }
23    public void draw1(Canvas canvas, Bitmap bitmap, int width, int height){
24        Random ran = new Random();
25        paint.setColor(Color.argb(255, 255, 0, 255));
26        paint.setStrokeWidth(StrokeWidth);
27        paint.setStyle(Paint.Style.STROKE);
28  　     canvas.drawLine(xPosition, yPosition, (xPosition + (width - bitmap.getWidth() * 2)), yPosition, paint);
29    }
30    public void draw2(Canvas canvas, Bitmap bitmap, int width, int height){
31        Random ran = new Random();
32        paint.setColor(Color.argb(255, 255, 0, 255));
33        paint.setStrokeWidth(StrokeWidth);
34        paint.setStyle(Paint.Style.STROKE);
35        canvas.drawLine(0, yPosition, left_widthX, yPosition, paint);
36        canvas.drawLine(left_widthX + bitmap.getWidth() * 2, yPosition, width, yPosition, paint);
37    }
38    public void move (Bitmap bitmap) {
39        yPosition += bitmap.getHeight() * 0.1;
40    }
41}
42