Question

E / Android运行时：致命异常：主要流程：com.marsad.wallapp，PID：20425 java.lang.ArithmeticException：除以零

嗨，当我单击gif图片以用作动态壁纸时，大多数情况下一切正常，但有时应用崩溃并显示错误

Logcat

E / Android运行时：致命异常：主要流程：com.marsad.wallapp，PID：20425 java.lang.ArithmeticException：除以零在com.marsad.wallappapp.GIFWallpaperService $ GIFWallpaperEngine.draw（GIFWallpaperService.java:139）在com.marsad.wallpaperapp.GIFWallpaperService $ GIFWallpaperEngine.access $ 000（GIFWallpaperService.java:82）在com.marsad.wallappapp.GIFWallpaperService $ GIFWallpaperEngine $ 1.run（GIFWallpaperService.java:111）在android.os.Handler.handleCallback（Handler.java:873）在android.os.Handler.dispatchMessage（Handler.java:99）在android.os.Looper.loop（Looper.java:224）在android.app.ActivityThread.main（ActivityThread.java:7139）在java.lang.reflect.Method.invoke（本机方法）在com.android.internal.os.RuntimeInit $ MethodAndArgsCaller.run（RuntimeInit.java:536）在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:876）

这是完整的代码


public class GIFWallpaperService extends WallpaperService {
    Context context;


    @Override
    public WallpaperService.Engine onCreateEngine() {

        Singleton b = Singleton.getInstance();
        String path = b.getPath();


        try {
            InputStream is = new FileInputStream(path);
            Movie movie = Movie.decodeStream(is);

            return new GIFWallpaperEngine(movie);

        } catch (FileNotFoundException e) {
            e.printStackTrace();
            Toast.makeText(context, "Error: " + e.getMessage(), Toast.LENGTH_SHORT).show();
            return null;
        }
        

    }


    private class GIFWallpaperEngine extends WallpaperService.Engine {

        private final int frameDuration = 20;
        private SurfaceHolder holder;
        private Movie movie;
        private boolean visible;
        private Handler handler;

        int width;
        int height;

        public GIFWallpaperEngine(Movie movie) {

            this.movie = movie;
            handler = new Handler();

        }

        @Override
        public void onCreate(SurfaceHolder surfaceHolder) {
            super.onCreate(surfaceHolder);

            this.holder = surfaceHolder;

        }

        private Runnable drawGIF = new Runnable() {
            @Override
            public void run() {
                draw();
            }
        };

        private void draw() {

            WindowManager wm = (WindowManager) getApplicationContext().getSystemService(Context.WINDOW_SERVICE);
            Display display = wm.getDefaultDisplay();
            float screenWidth = display.getWidth();
            float screenHeight = display.getHeight();

            width = (int) screenWidth;
            height = (int) screenHeight;


            if (visible) {
                Canvas canvas = holder.lockCanvas();
                canvas.save();


                canvas.scale((float) display.getWidth() / (float) movie.width(),
                        (float) display.getHeight() / (float) movie.height());
                movie.draw(canvas, 0, 0);


                canvas.restore();

                holder.unlockCanvasAndPost(canvas);
                movie.setTime((int) (System.currentTimeMillis() % movie.duration()));

                handler.removeCallbacks(drawGIF);
                handler.postDelayed(drawGIF, frameDuration);

            }

        }

        @Override
        public void onVisibilityChanged(boolean visible) {
            //super.onVisibilityChanged(visible);

            this.visible = visible;

            if (visible) {
                handler.post(drawGIF);
            } else {
                handler.removeCallbacks(drawGIF);
            }


        }

        @Override
        public void onSurfaceDestroyed(SurfaceHolder holder) {
            super.onSurfaceDestroyed(holder);
            this.visible = false;
            handler.removeCallbacks(drawGIF);
        }

        @Override
        public void onSurfaceChanged(SurfaceHolder holder, int format,
                                     int width, int height) {
            this.width = width;
            this.height = height;
            super.onSurfaceChanged(holder, format, width, height);
        }
        

        @Override
        public void onDestroy() {
            super.onDestroy();
            handler.removeCallbacks(drawGIF);

        }


    }

}

Answer 1

您的例外来自以下行：

            canvas.scale((float) display.getWidth() / (float) movie.width(),
                    (float) display.getHeight() / (float) movie.height());
            movie.draw(canvas, 0, 0);

不是你提到的。

由于这些行可能会被零除。

在进行计算之前，我将确保电影对象具有宽度/高度。

Answer 2

您可以在绘制之前检查一下

if(movie.width() > 0 && movie.height() > 0){
        canvas.scale((float) display.getWidth() / (float) movie.width(),
                (float) display.getHeight() / (float) movie.height());
        movie.draw(canvas, 0, 0);
}else{
        //do something default which suit your application
}

为什么我得到java.lang.ArithmeticException：除以零

2 个答案: