Monday, August 25, 2014

codility tests

i applied for a position and it required i did a test on
i hadn't tried it before and quickly failed, but i loved the concept and thought i should try all the example tests.
the most important for the codility tests i guess it the METHOD, and the site gives a good number of tests to  display a number of problems and methods for solving them.
some of the test problems i simply cannot solve on my own yet, others i may solve, but with scalability problems...

for example there was one problem were i did achieve Correctness of 100%, but Performance maxed at 60% (actually the first time i submitted my solution, the site decided that the code does manage 80% with O(N+M), but somehow it was wrong - all the other times it correctly detected O(N*M)).

i spent about an hour thinking what i got wrong, trying different fact quite often you may get a hint for the solution from the expected worst-case complexity - in this case it was O(N+M), generally meaning there should be two cycles, one on N and the other on M.
now, in my solution i had the N loop and within it was a M loop. I had been trying to optimize it in couple of ways but it was when i surrendered to the thought that having an inner loop will always give me O(N*M), that the final solution performance-wise struck me - now i knew what had to go to the second outer M loop and this got me 100% performance... the test name was MaxCounters, and while sometimes you would get quickly to a solution that at least will give you 100% Correctness, there are some problems that are quite difficult to grasp and apply

but like i said it is all about the METHOD, and given time and will, one should be able to hit all records

Saturday, June 21, 2014

The provider did not return a ProviderManifest instance (VS 2013, EntityFramework 6)

checking out EntityFramework 6 code-first and encountering various errors during the process :)

this is more of a saved hint how to deal with this...found in the comments here:

this comes with the inner exception of "Could not determine storage version; a valid storage connection or a version hint is required"

and what solved it was this comment:

Open the EDMX file and change ProviderManifestToken="2012" to ProviderManifestToken="2008"

judging by MS supports' comment, Microsoft seem terribly slow in keeping tools up to date with frameworks...whats the point in rushing when creating ugly problems for (early) adopters?

Saturday, October 05, 2013

AndroVM network setup for android apps testing

not sure how i got to, but the idea to have a faster emulation for android apps testing was great so when the time came i decided to put some time and set this up

the original source claimed that setting 'bridged adapter' worked for him so i followed this advice didn't work

this unleashed a couple of hours of testing different variants, scratching my head and searching on the web (btw is getting better, and while the results are not so comprehensive as google's, they still manage to provide the most essential hits, most of the time).

the search lead me to this result at, which in turn got me playing with virtualbox's host-only settings, and then after a moment of tense expectation...nothing...

another search lead me to this article:, where they mention that actually it is not the first adapter that needs to be configured, but the second one...back some testing which again didn't provide anything

i should mention that on virtual box i was looking into the androVM configuration screen, where the IP of the device did show up a couple of times, but i could never connect with adb.
i also installed terminal emulator on the virtual box device - i was surprised an first that it managed to connect to internet and download the app from market.

so after scrapping all the previous advices i started experimenting again and finally one of the combinations worked:

the only one, actually that worked is this:

host-only adapter on Adapter1
bridged adapter on Adapter 2

don't ask me why it worked, but in the end it did.
strange thing is that androVM  configuration screen doesn't show the ip. the terminal shows it in netcfg. also make sure the bridge adapter is bound to the actual working network adapter

now i have to figure out why my ActionBarSherlock application works on 2.2-2.3 devices, but the bar is not shown on 3.0, 4.0 etc... any ideas?

p.s. eclipse has no problem detecting the 'device' started on androVM, just tell it to detect running Android devices, connect to yours and off you go...

Thursday, September 19, 2013

image is rotated after camera preview in portrait mode (android)

this was quite a headache.
in surface preview (portrait) everything is fine, but once you save the image it turns out it is stored rotated on 90 degrees. what the heck?!

it seems a huge problem with some phones and checking some groups, android team has no intention to fix this, claiming it is manufacturer problem. ok.

there are many useful  discussions on (of course) with different suggestions. some of them quite ugly. i tried to go with the one to rotate the image back before saving, but then you cannot do this in every case because in landscape everything seems to work fine...grrrr...

ok, first lets see how may we know what mode we're in (landscape/portrait)

again a bunch of hacks and solutions...
- "width>heigh? you're landscape"
- check in mode the file itself was saved via exifinterface:
             exif = new ExifInterface(file.getAbsolutePath());

- blah blah blah

here's the one that works for me:
        Configuration newConfig = parentActivity.getResources().getConfiguration();
        if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) {
                Log.v(LOG_TAG, "detected landscape mode");
        } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT) {
            Log.v(LOG_TAG, "portrait mode detected");
 so how do we use this info?


now if we rotate the camera (and we're sure we're in the bloody portrait) will it save what is sees correctly? Noooooooooooo, the images is again rotated incorectly

ok, so lets rotate the image as well then

but here is another darn problem; "Out Of Memory" exceptions - first we get the byte[] of the image, then we create a bitmap out of it, and then try to rotate with a Matrix. well, you can't - BOoooM!

at least on my humble device

so you have to come up with some trick i guess

using square's excellent picasso wouldn't do the trick because even if it may rotate the image when it loads it, it cannot save it rotated back to storage.

wait a second, did you say "rotate the image when it loads it"?

so here is how we can trick the trickster - rotate the image on loading!

but we have to know if the image even has to be rotated, what if it has been saved in landscape mode and all is good? do we have to, like, open the file and read some information from it? blah...

well - there is an easier way - just give the file such a name that you'll know it has to be rotated when loaded, then it gets as easy as PI:

        if (filename.contains("MUSTBEROTATED")) {
            Picasso.with(activity.this.getApplicationContext()) //
            .load(new File(filename)) //
            .resize(screenWidth, screenHeight)
        else {
            Picasso.with(activity.this.getApplicationContext()) //
            .load(new File(filename)) //
            .resize(screenWidth, screenHeight)

and thats about it i guess

what remains to be seen is how this will work on devices that do not have this portrait nightmare problem...probably doesn' much for hacking glory...

Tuesday, September 03, 2013

rotate image in android apps

i guess i'm starting to learn a thing or two about organizing my stuff, and as result decided to post the result of one task that is a part of a bigger task, that is a part of an idea that i'm already getting tired of chasing...

my app has to display images and i want to be able to rotate them! sounds simple, and it is! especially with the miracle of Internet, GOOG and

so we have this imageview...
  ImageView imageView = (ImageView) findViewById(;

we're loading some picture onto it...
 Bitmap bMap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);

and turns out there is this lovely Matrix class, that exists for all kind of math abuses
                 Matrix mat = new Matrix();

so we can take the original bitmap and apply the matrix operation on it
                  Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0, bMap.getWidth(), bMap.getHeight(), mat, true);

and when we set this image on the imageView we expect to see the rotated image, right?

but somewhere something is wrong or some manual has not been read, cause a vital piece is missing: you have to set scale type on the imageView, (before assigning the new image?)

now this will work fine and will leave this highly uninformative post online, so i can remember how i did it!

i simply don't have the time to research the why's and do's - at least not right now that i'm still in prototyping phase and the steam has already began to ...steam away...
i lost a few days (all right - couple of hours over few days) with the rotate images problem and at least it made me learn to split bigger tasks into smaller ones - and how effective and helpful it can be!

Monday, August 26, 2013

android freeze

weirdest thing happened while i was experimenting with api.
i was testing on a 2.2 device and of course there were the problems with
Camera.getNumberOfCameras() missing etc, but when i got to the point to get a handle to the camera with a simple - nothing happened!

literally, because the app froze and nothing would unfroze it. it even blocked other applications trying to use the camera, and that until reboot of the device.

i thought maybe it happened because i was on the ui thread, but even as i pushed the camera code to an AsyncTask,doInBackground(), while the ui thread was responsive there was never response from the async portion

weird, a?

i read this was only fixed about API 5 releases and 3 years later. wow!

the obvious workaround is to use intent as i was originally planning, but is this really such a big, unsolvable problem? certainly there are apps that are using the api so how do they manage to workaround it? or maybe the problem is gone in the method, which is introduced in 2.3

in any case, android is fun. i wonder if you'd agree with this statement if you we're working on it for money under strict client requirements...

UPDATE 2013/09/06:

So there is a way to get handle of the camera, as i suspected in involves SurfaceView which i didn't want to get much into at the time of the previous writing as i was planning to use intent, but actually there are many examples for using SurfaceView out there and here is the code that worked for me:

    protected void onCreate(Bundle savedInstanceState) {


        surface_view = new SurfaceView(getApplicationContext());
        addContentView(surface_view, new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));

        if (surface_holder == null) {
            surface_holder = surface_view.getHolder();

        sh_callback = my_callback();
    SurfaceHolder.Callback my_callback() {     
        SurfaceHolder.Callback ob1 = new SurfaceHolder.Callback() {

            public void surfaceDestroyed(SurfaceHolder holder) {
                  mCamera = null;

            public void surfaceCreated(SurfaceHolder holder) {
                mCamera =;

                  try {
                  } catch (IOException exception) { 
                        mCamera = null; 

            public void surfaceChanged(SurfaceHolder holder, int format, int width,
                    int height) {
        return ob1;

this is all from the wonderful post at by Bharat Sharma

a very nice example of actually taking a picture is here:, by user jiahao

so stackoverflow has been getting huge over the view years, i still remember one of its founders writing a post about dreaming about such a hub of help for developers/admins and all kinds of people looking for qualified answers - well done!

Tuesday, January 01, 2013

hello github

i posted the code for the android app i mentioned earlier in github here:

since the app itself was my coding test for android platform, a good decision was to use it as test of github :)

must say that github's windows app is pretty cool, although i thought it was capable to do more - tortoiseSvn style maybe? still checking things around so it may turn more powerful yet, for now i'll do mostly with the git console

grasping git easier as i have svn experience, but i realise the two differ a lot, but i guess it is mostly on a higher/architecture level

in any case, it would be nice if someone found the code useful, and maybe even make it better

enjoy and a Happy New Year

2013 yeyyyy!