My code logic needs an SD card installed in the device. I have added a check for this case in the application's splash screen, but would like to inform users before they download/install this app. Is there a way to achieve this ?
Thanks !
There is no way to do this before the app installs, as the only way to limit such things is by using the <uses-feature> tag. However, that tag has no options for storage requirements. The best warning you can give is to prominently include it in your app description.
On the other hand, every device I've ever heard of an encountered has some form of external storage, be it a SD Card or inbuilt memory mounted as external storage. What you're doing by using the Splash Screen to check for the external storage is the best way to do this, as there is no other option.
There's no way to do that. Your app have to be installed to be able to check user's environment. You could try to to enforce SD card installation of your app, so if there's none Google Play might (not tested) simply not allow app installation at all, but it will not solve your problem as user will still do not know why. Solution is to clearly state in product description that SD card is mandatory. But note, that requiring SD card is risky as many devices does not have any while still offer external storage. My suggestion - just add note about storage requirements and let system deal with it.
I think it is NOT POSSIBLE . You are checking the sdcard on splash screen and prevent user for next process is the right solution or Use android:installLocation for install android application on sdcard.
Beginning with API Level 8, you can allow your application to be
installed on the external storage (for example, the device's SD card).
This is an optional feature you can declare for your application with
the android:installLocation manifest attribute.
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
android:installLocation="preferExternal"
... >
If you declare "preferExternal", you request that your application be
installed on the external storage, but the system does not guarantee
that your application will be installed on the external storage. If
the external storage is full, the system will install it on the
internal storage. The user can also move your application between the
two locations.
When your application is installed on the external storage:
There is no effect on the application performance so long as the
external storage is mounted on the device.
The .apk file is saved on the external storage, but all private user
data, databases, optimized .dex files, and extracted native code are
saved on the internal device memory.
The unique container in which your application is stored is encrypted
with a randomly generated key that can be decrypted only by the
device that originally installed it. Thus, an application installed
on an SD card works for only one device.
The user can move your application to the internal storage through
the system settings.
Look Here for more details .
Related
I'm new to Android and extremely confused about storage.
I have 4GB of internal storage on my Chromecast.
I plugged in a USB and formatted it as a storage device.
After that I enabled force push installs to external in the developer settings.
The drive name shows under the settings as USB Drive, however when I load File Commander App it's not showing at all.
When I used Termux and took a look at /mnt/sdcard/Android/obb to find a large OBB, it seems to be showing at exactly the same directory as /storage/shared/Android/obb.
So where exactly is internal storage and external storage?
How can I move files between them if I can't do so using File Commander?
In short, Internal Storage is for apps to save sensitive data to which other apps and users cannot access. However, Primary External Storage is part of built-in storage which can be accessed (for read-write) by the user and other apps but with permissions
Internal vs external storage is kind of a distinction that didn't go the way it was expected to go. I think originally it was meant to be phone storage vs SD drives, but it moved away from that. Now internal storage is special storage for an app held in phone memory. Its limited in size per app, but you should reliably be able to hold that amount. No other app can read this (unless your phone is rooted).
External storage is unlimited, but theoretically may be less reliable? You may also not be able to get any, if the device is out of space. But its not really removable anymore, so you can count on it staying there. It also is specific to your app and no other app can read it.
Then there's a few special folders in external storage anyone can access. Downloads, photos, etc. These work like external storage but data stored there can be accessed by other apps.
None of the app specific storage will show on file picker, because other apps don't have access. Unless you're rooted, in which case the rules can change. Or if you're using ADB and debugging.
As for where the actual folders are on disk- that can change depending on model. You can't depend on exact directory structure on Android. When you're writing a program that's why you use getFilesDir and getExternalFilesDir.
(If you're wondering why they still have a difference between the two- I don't know other than inertia. They've killed every difference between them, the little difference left may as well be killed to make programming simpler IMHO).
On my Samsung devices I put a file in the /Download folder. When I select the file within my app (via a file browser), the file is called /storage/emulated/0/Download/myfile.db. This name is stored in my app settings.
At the start of the app the file should be opened. First the app checks if the file exists. In some cases, say once every 2 weeks, the file is said to be not existing! This happens also at my friends mobile since half a year.
Why is that happening? For years everything ran smoothly.
This code runs for 6 years. Of course I added the permissions stuff.
Your help is much appreciated!
You can't use the Download as an guaranteed storage place for your files. You should use the Internal storage for the app. This is what Google has written about the download folder:
This space is called external because it's not guaranteed to be accessible—it is a storage space that users can mount to a computer as an external storage device, and it might even be physically removable.
Here you can read more about the Internal storage and the External storage in Android.
Here is some more information about the Download folder from Google.
Caution: The external storage might become unavailable if the user removes the SD card or connects the device to a computer. And the files are still visible to the user and other apps that have the READ_EXTERNAL_STORAGE permission. So if your app's functionality depends on these files or you need to completely restrict access, you should instead write your files to the internal storage.
I want my app to be installable only on internal storage.
I have tried two options:
Not specifying any storage preference in the manifest (the Docs say that this forces the app to install only to internal storage)
Explicitly specifying android:installLocation="internalOnly" in the manifest
In both cases, when I try to install it on a tablet that's running Android 4.4.2, Kernel 3.4.67, and having an SD card, it prompts me to select whether the app should be installed on Tablet Storage or the SD card.
The tablet has ample free internal storage (9 GB). The default write disk is also set to Internal Storage.
Is there any way to bypass this prompt and install to internal storage after the user approves the permissions needed by the app?
According to the docs, the flag you are using should not allow install on the SDCARD or any external storage. This appears to be a bug.
Post at the bug location to help give it attention.
I was wondering, when we download an app which is very cool but before you install it ask to give permission for almost everything you have on the phone. Even that app can make call without your permission to your contacts. Given this scenario, how do we say an unrooted device where app data is secured from other app access? if I have an app which stores data on the device memory then would that be accessed by one of those app which takes all permission before installed?
Thanks in advance for your response.
Apps are still sandboxed, they can't access each others internal storage even with requested permissions.
I'm not sure this is the correct forum for your question though as it's not related to developing. This isn't the right site for IT support.
Edit
As mentioned in the comments - anything put somewhere insecure location such as the SD card would be readable, but the default file storage is a bit more secure.
From the android docs (http://developer.android.com/training/basics/data-storage/files.html)
Note: Your app's internal storage directory is specified by your app's
package name in a special location of the Android file system.
Technically, another app can read your internal files if you set the
file mode to be readable. However, the other app would also need to
know your app package name and file names. Other apps cannot browse your internal directories and do not have read or write access unless you explicitly set the files to be readable or writable.
In android, whats the difference between external storage that is nonremovable (internal) and the internal storage? I am not sure where to save my data. I just need to save a game stats that a person can pull anytime they want
Thank you
In many newer devices there will no longer be a physical distinction, with "internal" and "external" storage sharing the same flash chips without necessarily even having fixed allocation, so the difference really remains one of intended access paradigm.
Files on the external storage (real or simulated) are unavoidably shared with everything, and modifiable by anything with that manifest permission. Traditionally they are easily visible, though with the recent MTP-access devices the system may need to be told about them before a connected PC will see them.
In contrast, files on the internal storage are private to an application, excepting anything running as root or system, or if the application has decided to make them generally visible or changeable. Even when accessible, data on the internal storage can be more difficult to access outside the owning app - it's not supported by the consumer-targeted USB Mass Storage or MTP mechanisms, and even for other apps and development tools it is tricky to locate unless you know where to look, as while you may be able to examine files folders which applications have chosen to share, you cannot browse through the parent (typically /data or /data/app) folders. It can be a bit frustrating even for the developer of an app to access the files it creates on private storage during debugging (though while the apk is debuggable it is possible with the run-as tool and adb, or you can build an export capability in to the app, or run on the emulator where adb has root).
Likely your decisions process should be something like this: Is it meant to be private to the owning application? If so, put it on the internal storage, unless it's too big and targeted at older devices, in which case you may need to encrypt and/or sign it for protection before placing on the external storage. Otherwise, if it's meant to be shared, needs to be handed to arbitrary other components (email app, etc), or is big, put it on the external storage.
In android, whats the difference between external storage that is nonremovable (internal) and the internal storage?
External storage never meant removable. It always meant "accessible by the user by plugging in a USB cable and mounting it as a drive on a host computer". Early Android devices happened to have removable external storage, but that was never the definition.
Internal storage is storage that is not accessible by the user, except via installed apps (or by rooting their device).
Further to Chris' answer if you are concerned about external storage (SD card), not being avilable you can simply check this every time your app loads up and then pull in the relvent information accordingly.
You can use something like this:
if(isSDPresent)
{
// SD Card is present
// Your code goes here, files will be located # /mnt/sdcard/Android/data/packagename
}
else
{
// SD Card is not presenet
// files located here /data/data/packagename
}
If you are testing on an emulator, you can load up your DDMS and find all the files stored in the revlent places.
Hope this helps.