Android Trial App - android

I'm trying to implement a trial app
I've searched this place,
no solutions found.
I know on PC some program can impose trial-day limit without reading system time,
how do they do it???

Here, this might help: http://developer.android.com/guide/publishing/licensing.html
Though really, I think you wold have to do trial-day based on system time, still using the licensing service, though.
I personally have not used the app licensing, but glancing over it, it looks like it would work.

Well the simple approach will be to store the date when the app is first opened. And each time the app is opened, just check the date and proceed accordingly. You can save the data in either a file or the database.

Related

is it possible to program an app that receives data from an already existing app?

I'm trying to program an app using android studio that receives data (blood sugar levels) from the app tomato (which calculates blood sugar levels automatically every 5 mins or so). The tomato app already exists and is made by a company.
So I was wondering if doing this is possible. if so, how?
I saw this post: Is it possible for an Android app to use data from another app? which is very similar to what im trying to do but i didnt find an exact solution/answer to this.
Any opinions and help are very much needed and welcomed.
You would first need to know how the app is storing the data, you could check your phone's storage using the Device File Explorer in Android Studio. If they have exposed the data then you are able to check and read the files that the app has exposed. However, I have a feeling that they would not be leaving them in plain text for you to take.
Upon some further reading, it seems they read from a device called a MiaoMiao Transmitter. You could ask the producer of this product for a developer kit and see what they say. This would come with documentation as to how you can get data from the product. However, if they do not provide you with any help, you will need to do some investigation as to how the device functions.
Perhaps it sends android broadcasts when it is taking a reading? This is just speculation of course. This is very niche and I believe that is a reason there are only a few apps that use the device - they are trying to lock out "non-verified" developers. However, when there is a will, there is always a way! ;)
Best of luck!

Android App with HTML/CSS/jQuery. [How] Can it be done?

I know this has been asked before (did not find a straight forward answer) but can I (Or how can I) create and Android App using CSS/HTML/Jquery ?
I will not need to hook into native functions, such as the accelerometer, camera, or even the Toast Messages...I only need to create an app to show a list of names and some details when name is selected, therefore I don't know if it's worth learning to make my life more complicated for something like this.
PS: I need the app to work offline, otherwise I would have just made it with jQuery Mobile and uploaded it on a server.
UPDATE AFTER GETTING DOWNVOTED
Ok, so I get downvotes for this question, probably because it's been asked before, or maybe not, since he/she didn't take the time to write a reason...
Anyway, my point is: I did googled it and searched, but at this moment there are a lot of ads of websites and web apps that will help you do this BUT are they reliable, safe..do they really do the trick or it comes with bugs? That is why I asked the question, to see who used what and what was their experience with it. So yeah, you can downvote me for not trusting every ad and not taking the time to try out everything out there!
Well you can use https://software.intel.com/en-us/html5/tools to develop cross-platform apps. I used it to develop too. It is quite good but it only has one major issue: you can't use php. It also enables you to do on-device testing.

How to retrieve app usage statistics of an android device?

I'm constantly trying new apps and my phone is getting cluttered with old apps, I no longer use. So, I thought I'd develop a simple app to help me out. There are similar apps, but none does exactly what I want:
I would like to have a list of apps which I've installed in the last month, which I've used X number of times (for easy access: They may be keepers!) as well as those I've not used in Y weeks.
Is there any way to get app usage statistics with Android? I guess ActivityManager might help me to gather that statistics, but is there a way to read just when an app has been used last? Or how many times in a given period?
Any tips will be most welcome :)
You can try out my app for uninstallation of the apps you don't need : https://play.google.com/store/apps/details?id=com.lb.app_manager .
Also, if you wish to find exact usage statistics of your apps, you can use my app this way: find "settings" (the app itself) inside the list (you can perform a search query), choose to make a shortcut of it, and then choose on the dialog "Usage Statistics". This way you can perform both the operations you wanted.
I also plan on adding this feature somehow in the future, but that's what you can do for now.
Here's a screenshot (it's the first on what I show here) :

How can we get two-way synchronization in Android using the existing contact list?

I spent a long time searching and reading the Internet looking for that answer.
I'm pretty sure I found it, but in case I miss something big, I'm here to ask.
As I understood, it is simply not possible to have a two-way synchronization based on existing contact in Android (for now)
While I was looking I became familiar with the Android SDK and for example all the sync management part.
So today I'm going to ask you: DID I MISS SOMETHING?
And because I'm sure I don't: HOW DO YOU DO when you want to sync the local contact book with your service?
I really prefer something clean (as every developer want) but I can't figure it out myself.
EDIT: By two-way synchronization I meant full and real sync as user (or developer) will expect.
If any change occur on the phone the information goes to the server and if any change occur on the server it works as well. Any change includes adding/updating and deleting.
I'm aware of the ContentObserver method but the way it works with contact doesn't allow to get satisfying results. It seems that this part as been made difficult by google itself
Thanks for helping

How often to check for license?

My main activity is basically useless without another activity (act2). act2 can be accessed from a button in the main activity. It is also available through a home screen widget, which when clicked calls my main activity and immediately calls act2.
Right now, I have it set to check license anytime the function that handles the button click is called. This covers the button press in the main activity as well as if you come from the widget.
My question is, is this too often? Is getting a cache response anymore draining than checking a variable for example?
I have tried putting it on onCreate but when it says it's not licensed, you can just close the application and open it again and it will not run through onCreate again.
Here I assume you've read all the licensing documentation, and that you're using the SDK. You said nothing, so I'm going for the "defaults". There are a few clues on the Android developers blog as well as on the Internet.
I asked myself the same question last year. Or at least something similar. So let's go one step at a time:
My question is, is this too often? Is
getting a cache response anymore
draining than checking a variable for
example?
I would say that the difference is going to be "imperceptible" to "not much". First of all, the validity timestamp (VT field from extras) is stored locally, properly encrypted/obfuscated. I'm assuming you're using the ServerManagedPolicy policy, since you said nothing about it.
Depending on the kind of the app, we should notice that you may be even writing things on onPause, for example (checking for changes if applicable, of course). So, I wouldn't worry about it.
But because there is no perceptible harm does not mean you should do something. That's why I disagree with what Kerin posted:
I'm sure you'll stop loads of piracy and you aren't wasting your time at all.
More on that later. For now I say that you shouldn't need to do lots of checkings. That's what the policies are for. They handle it probably better than you and me. Anything else is indeed a waste. Personally, I only do checkings on onCreate (obviously), and also in one more situation rarely used (but very important on the app usefulness).
What you should do, however, and I say because nobody said here yet, is properly obfuscate and change the LVL library, as well as your own code side (the checkerCallbacks). Here, I changed a lot of things on the LVL library, including some simple single key cryptography (weak), and also changed how the interfaces are implemented, and how arguments are passed, and so on. Basically, I created my own LVL after posting that question here on SO.
On the opposite of what you're doing, I also customized the VT field in order to mandate a minimum time for the validity of the cached response. That's why my app is to be used in the wild, where net access is not always available. Those subtle details depend on your app, what it does, how it does, where people would be using them.
If you're a developer, it's easy to forget about the user. There is nothing worse than a legitimate user being denied access to an app he bought. So far, I didn't have problems (I check usage statistics and compare to my account), but I believe games have more trouble (it's typical of that field).
So, returning to my constructive (please, we are all trying to learn here, myself included) critic about Kerin's post, I would say that even LVL itself is not enough to "stop loads of piracy".
If you know anything about how Android works, you'd know that the apks can be easily decrypted to source code, just use dex2jar and jdgui (Google them). In fact, I always decrypt my apps before publishing to check if everything is working the way it should. And take into account that I never did computer college, I just happened to learn java and Android to create my own app that I needed and was unavailable for Android (a tide app for my country). I'm sure there are hackers and techies much smarter out there that can do even more.
People start thinking that LVL will stop piracy, and then learn the ugly truth and be disappointed. That's not what the LVL is for. Just look at the code... it was made to avoid "automated" piracy. It is to force someone to personally look into the code, see how it works, and then "switch" the proper flags, if he can make sense of them. But then again, if you use proguard, it will make the task horrible, exhaustive (believe me, that's why I use dex2jar + jdgui myself).
If your app is being sold for $1 or even around $5 or more, it will make this trouble not worth it. That's my stance on the LVL. Obviously, if you have an niche app that costs $100, for example, you probably can do it properly, server side, with public keys. But I feel that it's not the case here.
Anyway, just my 2 cents.
You can check for the license for the first time, then cache it. The next time when your app runs, read the license from the cache, and also start a Thread that gets the license from your server. If the license that you got from the server is now invalid. You can pop up a dialog box to tell the user that the license is invalid, remove the cached license, and quit the app.

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