Camera Null Pointer Exception

Question

I am new to Android. Trying to make a BarCode reader application. Getting the following error. Can anyone help? My application stops responding on start.

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

Here is my code:

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

Check if you didn't forget to add the camera permission in manifest.

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