Develop Reference

Qt and app data storage in Android

I am working on a mobile app, using Qt/C++, right now focusing on Android.
My app needs to store some permanent data, in a private and secure way (not accessible to other apps, protected as much as possible):
some basic key/value settings: QSettings seems to be what I need here. The question being where does this end up in Android, is it stored in the shared preferences section?
binary files, such as a few pics (these are created by the app, not static resources). I would have stored this in an internal storage file; where would I store this in Qt? Do I use Qt's file capabilities, and java calls to find my app's internal storage folder, or is there a Qt object designed for that?
Thanks.

Android maintains a standard storage for applications under the path /data/user/0 , where each application gets storage space. so if you have an application named org.qtproject.example.myApp, Android automatically creates storage space for this app:
/data/user/0/org.qtproject.example.myApp
The settings are stored under the files folder of this path, as ../files/.config/OrganizationName/AppName.conf
When you want to store information in Android you don't use absolute paths, instead you specify the location of your storage using Qt QStandardPaths which usually returns location under the application path mentioned above, so for example to store a file mySomeFile, you would set the path using QStandardPaths like:
auto path = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
auto fileName= path + "/mySomeFile";
and the file is stored as :
/data/user/0/org.qtproject.example.myApp/files/mySomeFile

Create folder inside android folder of android device

We all know there is always a folder in android named Android which always contains data of app.
I saw many app folder inside it which store their file there.
So my question is how can i create a folder inside android folder of an android device and store my application data inside of it?
Please suggest something

We all know there is always a folder in android named Android which always contains data of app
I am assuming that you are referring to the Android/ directory seen in what the Android SDK refers to as external storage.
how can i create a folder inside android folder of an android device and store my application data inside of it?
Use getExternalFilesDir(), getExternalCacheDir(), or getExternalMediaDir(), all methods available on implementations of Context, such as Activity and Service.
Also, if you want to be able to see the files that you create from your desktop OS, you will need to arrange to have the files indexed by the MediaStore.

Android adding files on install

Is there any way to add files in Android storage on install? Like some image/video that will be stored there on install and if needed it would be loaded, like pushing a button or something like that ?

Is there any way to add files in Android storage on install?
Not really. You are welcome to package files as assets, then copy them to internal storage on first run of your app. Or, depending on what sort of file it is and what you want to do with it, you might be able to just use the original copy of the file as an asset directly.

How do I access my app's package folder in Android using Adobe AIR / Flex?

I have an application for Android built using Flex. I need to save some configurations and data so I want to know how I can access the package-specific folder for my app instead of creating my own folder and writing there.
The package-specific folder I'm talking about is at /sdcard/Android/data/com.mysite.myapp/. Do I just access it directly via that path or is there a variable for File class that I'm not aware of?
The reason why I want to save onto this folder is because, if I create my own folder and save there, that would require my app to request the permission to access SD card contents. Something I don't want to include in my permission list.

For app specific files, you can choose either applicationDirectory (read only), or applicationStorageDirectory.
http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/filesystem/File.html

Best way to do a separate data install on Android

I want to decouple data from code on my Android application, and I am not sure of the best way to do that.
For instance - with the Linux Mahjongg game you can add new tiles to the game by dropping a specially formatted file into a specific directory. The Mahjongg game checks that directory when it starts up.
I want to do the same thing with my Android app - I want to be able to install the app, and then have separate installs for different data files. It's the data file installs that have me hung up. I do not want to have to set up my own server and write my own download code.

You can ship the data with the installer app, then use Input/Output Streams to copy the data from the assets or raw dirs.
Check this out:
Ship an application with a database
The answer has an implementation of in/outputstream. You don't need to use a db, just copy the file to ext storage.
One important detail: if you put the file in assets, it will be shipped compressed, and the phone/tab will try to uncompress the file in its entirety in memory. One (hocky) way to avoid that is to name the file .mp3. Assets in .mp3 format are not compressed. (Hey! I said it was hocky!)
The installer app can either uninstall itself by using ACTION_DELETE in an intent (see http://android.amberfog.com/?p=98 for details) or just show a msg to the user that it's safe to delete the data app.
HTH,
llappall

by dropping a specially formatted file into a specific directory
You can do that on external storage. Create a directory, and check it when your app starts up for new files. Tell the user they have to stick the magic files in the magic directory for it to work.