Исключение камеры Null Pointer

Question

Я новичок в Android. Попытка сделать приложение для чтения BarCode. Получение следующей ошибки. Может ли кто-нибудь помочь? Мое приложение перестает отвечать при запуске.

09-10 15:11:52.987 26982-26982/com.aaa.Prototype E/AndroidRuntime﹕ FATAL EXCEPTION: main 
    java.lang.NullPointerException 
      at com.aaa.Prototype.CameraManager.setCameraDisplayOrientation(CameraManager.java:231) 
      at com.aaa.Prototype.CameraPreviewView.surfaceCreated(CameraPreviewView.java:54) 
      at android.view.SurfaceView.updateWindow(SurfaceView.java:622) 
      at android.view.SurfaceView.access$000(SurfaceView.java:90) 
      at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:185) 
      at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:680) 
      at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2217) 
      at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1211) 
      at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5039) 
      at android.view.Choreographer$CallbackRecord.run(Choreographer.java:776) 
      at android.view.Choreographer.doCallbacks(Choreographer.java:579) 
      at android.view.Choreographer.doFrame(Choreographer.java:548) 
      at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:762) 
      at android.os.Handler.handleCallback(Handler.java:800) 
      at android.os.Handler.dispatchMessage(Handler.java:100) 
      at android.os.Looper.loop(Looper.java:194) 
      at android.app.ActivityThread.main(ActivityThread.java:5433) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:525) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:924) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:691) 
      at dalvik.system.NativeStart.main(Native Method) 
09-10 15:11:53.592 26982-27015/com.aaa.Prototype D/dalvikvm﹕ threadid=11: interp stack at 0x5e2e6000 

Вот мой код:

public class CameraManager { 
    /** 
    * Fraction of bounds size in view 
    */ 
    private static final double BOUNDS_FRACTION = 0.6; 
    /** 
    * Fraction of height of bounds in view 
    */ 
    private static final double VERTICAL_HEIGHT_FRACTION = 0.3; 

    /** 
    * Camera instance 
    */ 
    private Camera camera; 
    /** 
    * Id of camera instance 
    */ 
    private int cameraId; 
    /** 
    * Current orientation of camera 
    * Possible values : 0, 90, 180, 270 
    */ 
    private int orientation; 

    public CameraManager() { 
     this.camera = getCameraInstance(); 
    } 

    /** 
    * Getter for camera 
    * 
    * @return camera instance, if it has been initialized 
    */ 
    public Camera getCamera() { 
     return camera; 
    } 


    /** 
    * Starts preview of camera, if it has been initialized 
    */ 
    public synchronized void startPreview() { 
     if (camera != null) { 
      camera.startPreview(); 
     } 
    } 

    /** 
    * Stops preview of camera, if it has been initialized 
    */ 
    public synchronized void stopPreview() { 
     if (camera != null) { 
      camera.stopPreview(); 
     } 
    } 

    /** 
    * Release camera, if it has been initialized 
    */ 
    public synchronized void release() { 
     if (camera != null) { 
      camera.release(); 
      camera = null; 
     } 
    } 

    /** 
    * @return if camera has been initialized<br/>(<code>camera != null</code>) 
    */ 
    public synchronized boolean hasCamera() { 
     return camera != null; 
    } 

    /** 
    * @return bounding rect for ui 
    */ 
    public final synchronized Rect getBoundingRectUi(int uiWidth, int uiHeight) { 
     double heightFraction = BOUNDS_FRACTION; 
     double widthFraction = BOUNDS_FRACTION; 
     if (orientation == 90 || orientation == 270) { 
      heightFraction = VERTICAL_HEIGHT_FRACTION; 
     } 

     int height = (int) (uiHeight * heightFraction); 
     int width = (int) (uiWidth * widthFraction); 
     int left = (int) (uiWidth * ((1 - widthFraction)/2)); 
     int top = (int) (uiHeight * ((1 - heightFraction)/2)); 
     int right = left + width; 
     int bottom = top + height; 

     return new Rect(left, top, right, bottom); 
    } 

    /** 
    * @return bounding rect for camera 
    */ 
    public final synchronized Rect getBoundingRect() { 
     if (camera != null) { 
      Camera.Size previewSize = camera.getParameters().getPreviewSize(); 
      int previewHeight = previewSize.height; 
      int previewWidth = previewSize.width; 

      double heightFraction = BOUNDS_FRACTION; 
      double widthFraction = BOUNDS_FRACTION; 
      if (orientation == 90 || orientation == 270) { 
       widthFraction = VERTICAL_HEIGHT_FRACTION; 
      } 

      int height = (int) (previewHeight * heightFraction); 
      int width = (int) (previewWidth * widthFraction); 
      int left = (int) (previewWidth * ((1 - widthFraction)/2)); 
      int top = (int) (previewHeight * ((1 - heightFraction)/2)); 
      int right = left + width; 
      int bottom = top + height; 

      return new Rect(left, top, right, bottom); 
     } 
     return null; 
    } 

    /** 
    * executes <br/> <code>camera.setOneShotPreviewCallback(callback)</code> if <br/> 
    * <code>camera != null</code> 
    * @param callback callback to provide 
    */ 
    public synchronized void requestNextFrame(Camera.PreviewCallback callback) { 
     if (camera != null) { 
      camera.setOneShotPreviewCallback(callback); 
     } 
    } 

    /** 
    * A factory method to build the appropriate LuminanceSource object based on the format 
    * of the preview buffers, as described by Camera.Parameters. 
    * 
    * @param data A preview frame. 
    * @param width The width of the image. 
    * @param height The height of the image. 
    * @return A PlanarYUVLuminanceSource instance. 
    */ 
    public synchronized PlanarYUVLuminanceSource buildLuminanceSource(byte[] data, int width, int height, Rect boundingRect) { 
     switch (orientation) { 
      case 0: 
       //data = flip(data); 
       break; 
      case 90: 
       rotate90(data, width, height); 
       return new PlanarYUVLuminanceSource(data, height, width, boundingRect.top, boundingRect.left, 
         boundingRect.height(), boundingRect.width(), false); 

      case 180: 
       break; 
      case 270: 
       rotate90(data, width, height); 
       break; 
     } 

     return new PlanarYUVLuminanceSource(data, width, height, boundingRect.left, boundingRect.top, 
       boundingRect.width(), boundingRect.height(), false); 
    } 

    /** 
    * Rotates image data 
    * @param data raw image data 
    * @param width width of image 
    * @param height height of image 
    */ 
    public void rotate90(byte[] data, int width, int height) { 
     int length = height * width; 
     int lengthDec = length - 1; 
     int i = 0; 
     do { 
      int k = (i * height) % lengthDec; 
      while (k > i) k = (height * k) % lengthDec; 
      if (k != i) swap(data, k, i); 
     } while (++i <= (length - 2)); 
    } 

    /** 
    * Sets camera display orientation depending on current activity orientation 
    * @param activity activity, which holds camera preview 
    */ 
    public void setCameraDisplayOrientation(Activity activity) { 
     android.hardware.Camera.CameraInfo info = new android.hardware.Camera.CameraInfo(); 
     android.hardware.Camera.getCameraInfo(cameraId, info); 
     int rotation = activity.getWindowManager().getDefaultDisplay().getRotation(); 
     int degrees = 0; 
     switch (rotation) { 
      case Surface.ROTATION_0: 
       degrees = 0; 
       break; 
      case Surface.ROTATION_90: 
       degrees = 90; 
       break; 
      case Surface.ROTATION_180: 
       degrees = 180; 
       break; 
      case Surface.ROTATION_270: 
       degrees = 270; 
       break; 
     } 

     int result; 
     if (info.facing == Camera.CameraInfo.CAMERA_FACING_FRONT) { 
      result = (info.orientation + degrees) % 360; 
      result = (360 - result) % 360; // compensate the mirror 
     } else { // back-facing 
      result = (info.orientation - degrees + 360) % 360; 
     } 
     orientation = result; 
     camera.setDisplayOrientation(result); 
    } 


    /** 
    * A safe way to get an instance of the Camera object. 
    */ 
    private Camera getCameraInstance() { 
     Camera c = null; 
     try { 
      cameraId = 0; 
      c = Camera.open(); // attempt to get a Camera instance 
      Camera.Parameters p = c.getParameters(); 
      p.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO); 
      c.setParameters(p); 
     } catch (Exception e) { 
      Log.e(CameraManager.class.getSimpleName(), "Camera error", e); 
      // Camera is not available (in use or does not exist) 
     } 
     return c; // returns null if camera is unavailable 
    } 

Answer 1

Проверить, если вы не забыли добавить разрешение камеры в манифесте.

uses-permission android:name="android.permission.CAMERA"