method called after release() exception unable to resume with android camera

while developing a camera app i'v encountered an exception that only happend when I switch to other intent (onPause for my app) or go to preference in my app(same, onPause)

01-15 17:22:15.017: E/AndroidRuntime(14336): FATAL EXCEPTION: main

01-15 17:22:15.017: E/AndroidRuntime(14336): java.lang.RuntimeException: Method called after release()

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.hardware.Camera.setPreviewDisplay(Native Method)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.hardware.Camera.setPreviewDisplay(Camera.java:357)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at com.sora.cbir.yuki.image.leaf.CameraPreview.surfaceCreated(CameraPreview.java:32)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.SurfaceView.updateWindow(SurfaceView.java:551)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.SurfaceView.onWindowVisibilityChanged(SurfaceView.java:213)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.View.dispatchWindowVisibilityChanged(View.java:4075)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:742)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:742)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:742)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:742)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.ViewRoot.performTraversals(ViewRoot.java:858)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.view.ViewRoot.handleMessage(ViewRoot.java:1995)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.os.Handler.dispatchMessage(Handler.java:99)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.os.Looper.loop(Looper.java:150)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at android.app.ActivityThread.main(ActivityThread.java:4389)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at java.lang.reflect.Method.invokeNative(Native Method)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at java.lang.reflect.Method.invoke(Method.java:507)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:849)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:607)

01-15 17:22:15.017: E/AndroidRuntime(14336):    at dalvik.system.NativeStart.main(Native Method)

i did some research and found out i need to add

mCamera.setPreviewCallback(null);

as a workaround for android's camera stack

my onPause now looks like this:

@Override

protected void onPause() {

    super.onPause();

    try

    {    

        // release the camera immediately on pause event   

        //releaseCamera();

         mCamera.stopPreview(); 

         mCamera.setPreviewCallback(null);

         mCamera.release();

         mCamera = null;



    }

    catch(Exception e)

    {

        e.printStackTrace();

    }

}

and my onResume:

@Override

protected void onResume()

{

    super.onResume();

    try

    {

        mCamera.setPreviewCallback(null);

        mCamera = getCameraInstance();

        //mCamera.setPreviewCallback(null);

        mPreview = new CameraPreview(Imageupload.this, mCamera);//set preview

        preview.addView(mPreview);

    } catch (Exception e){

        Log.d(TAG, "Error starting camera preview: " + e.getMessage());

    }

}   

}

and finally my getcamerainstances class:

public Camera getCameraInstance(){

    Camera camera = null;

    try {

        camera = Camera.open(); // attempt to get a Camera instance

    }

    catch (Exception e){

        // Camera is not available (in use or does not exist)

    }

    Camera.Parameters parameters = camera.getParameters();

    //mPreviewSize = getBestPreviewSize(parameters, wt, ht);

    //mPictureSize = getBestPictureSize(parameters, wt, ht);

    //Shift W & H => if camera rotates 90 deg



    mPreviewSize = getOptimalPreviewSize(parameters, wt, ht); //original => wt,ht

    mPictureSize = getOptimalPictureSize(parameters, wt, ht); //original => wt,ht



    Log.d("CAMERA", "SCREEN RESOLUTION H: "+ht);

    Log.d("CAMERA", "SCREEN RESOLUTION W: "+wt);



    Log.d("CAMERA", "PREVIEW RESOLUTION H: "+mPreviewSize.height);

    Log.d("CAMERA", "PREVIEW RESOLUTION W: "+mPreviewSize.width);



    Log.d("CAMERA", "PICTURE RESOLUTION H: "+mPictureSize.height);

    Log.d("CAMERA", "PICTURE RESOLUTION W: "+mPictureSize.width);

    //set preview size based on device screen

    parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);

    //set picture size based on device screen

    parameters.setPictureSize(mPictureSize.width, mPictureSize.height);

    //set output camera mode

    parameters.setPictureFormat(PixelFormat.JPEG);

    //set focous mode

    parameters.setFocusMode(FOCUS_MODE_AUTO);

    //set flash mode

    parameters.setFlashMode("auto");

    List<int[]> fps = parameters.getSupportedPreviewFpsRange();

    //System.out.println("FPS size: " +fps.size());

    //System.out.println("MAX FPS:"+(fps.get(fps.size()-1)[1])/1000);

    //log min and max camera supported fps

    Log.d("CAMERA", "CAMERA MAX FPS: "+(fps.get(fps.size()-1)[1])/1000);

    Log.d("CAMERA", "CAMERA MIN FPS: "+(fps.get(fps.size()-1)[0])/1000);

    if(camera_fps)

    {

        parameters.setPreviewFpsRange(fps.get(fps.size()-1)[1], fps.get(fps.size()-1)[1]);

    }

    //set camera parameters

    camera.setParameters(parameters);



    Toast.makeText(getApplicationContext(), "Your device are capable of previewing @" + fps.get(fps.size()-1)[1]/1000+"fps!",Toast.LENGTH_SHORT).show();

    return camera; // returns null if camera is unavailable

}

any ideas on how to resolve the exception?