Develop Reference

What is Android 11's equivalent of '/dev/null'

Android 11 introduced multiple changes to file storage and access. Apparently one of them is that one can no longer target output to '/dev/null' (my scenario is actually exactly explained in this old question).
Although the cited question solved the particular issue, one thing remains unanswered: what is Android 11's equivalent to '/dev/null'. That is, if one does not need the output of a particular operation (and in our case it is an operation that creates a biggish file).

Eventually I ended up solving my problem the following way (answer tailored to MediaRecorder problem but can be generalized to other situations too):
fun MediaRecorder.setOutputFile(context: Context) {
val tmpRecordingFolder = File(context.filesDir, "tmp_media")
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
setOutputFile(File(tmpRecordingFolder, "recording.mp3"))
} else {
setOutputFile("/dev/null")
}
}
Basically I am setting the output to be in the internal storage. I hope the file will not get huge and I am deleting the file in as many places in the code as possible. This seems to work on newer devices, currently have not yet ran into storage problems either, but the solution is not rolled out to production yet. Will update my answer if problems are identified.

I had the same issue, you'll have to specify a path since MediaRecorder crashes in Android 11 if you don't provide it, in order to avoid writing a massive file you could try to flush the file by stopping / restarting MediaRecorder, I been dealing with this issue for a few days too.
I replied a more detailed answer here: MediaRecorder Android 11 start failed -1004

Write logs to Android logcat without using standard apis

I want to implement __android_log_write() functionality using write() or some api available in libc(actually ulibc). The reason being that i cannot use any libraries associated with android as that would increase the memory required. I have very limited amount of memory as my code is running in separate memory region reserved during boot up. Main goal is to attach my debugging logs to logcat.
I am looking something similar to this:
write(1,"sandy",6);
The abovce code i can directly write to stdout. Similarly, i want to use write() or something else and write to logcat. What is the clean way to do it.
Hope i am clear. Thanks.

Got the answer. We need to open /dev/radio and write into them.
Thanks

RandomAccessFile on Android

I have a file on android phone which I would like to securely wipe it.
I read this.
It mentions This is especially true on mobile devices containing flash, which has wear-leveling to prolong its life and isn't guaranteed to overwrite the same block internally when you overwrite a block on the filesystem.
So, if I would to use the code on.Would it securely wiped on android phone ? Or when I use RandomAccessFile to write data to the file, it would be on a new block instead of the original block ?
Is it totally 100% impossible to get known of the exact block pointer on android ?
Or I have to recursively create a file, write with random data until the storage space hits the max. Then I try to edit the file I wish to delete. Which the flash will be force to use the original block while I rewrite the content and delete it.

Try to read the documentation about the Objects and Methods used in the code you mentioned This , nothing points that you write over the real Blocks used to save the file, and note the file can be written in Non-Sequential blocks, i think my friend told me about article discuss this issue, and they solved it using C++.

Creating a file on an Android device

I am new to Android development using eclipse, although not new to software development in general.
For my first real project, I am trying to modify the example SoftKeyboard that is supplied with the SDK. I want to modify one of the keys to act as a function key, when followed by a single letter key it will enter a canned string - performing a macro function.
So far so good. I have the key and graphics modified, and found where to respond. I would like to put the canned strings in an editable Properties file stored where the keyboard can find them.
That is where I'm having trouble. It seems that I can't to create and save a file. I don't know if it's read/write permission problem, whether the keyboard (it runs as a service) is not allowed to create a file, or my code is just plain wrong.
Can someone help me out – point me in the right direction?
Thank you very much.
Barry.

If these are canned files that come with the APK you install to the device and only need to read (not write), you can place them in the assets folder of your project. Then use the resource manager to load them:
Resources resources = getResources();
InputStream moduleSearchTemplateIn = resources.getAssets().open("file/name/here.properties");
If you want to read/write files on the SD card, you'll need to add a permission to your manifest. Though, for this purpose, I'd probably prefer a SQLite table.

Archiving mechanism

I'm working on an archiving mechanism of my application's log files and would like some advice.
What I want to do: When receiving a LogEntry, the LogListenerService will save it in a buffer and at some point it will print all the log entries in a file. When the file reaches a certain size an archiving service is called that will zip the contents of the log files and clean it.
I've implemented most of the functionality but have some questions:
How do I go about defining the ideal size of the buffer?
How do I make sure the log file size is kept under a given "maximum size"?
Thanks

Answering my own question.. :)
Depends on the application but the maximum memory an application can use is 16MB.
Simply by adding a check before writing to the file (I was hoping for a cleverer way)

Have you considered e.g. DroidDrop instead of rolling your own? (Caveat: haven't tested it myself yet.)