libcore | cross platform abstraction layer for C development

I was trying to download an image from a server and save it in the external memory, but in Android 11 it gives me an error when I try to create the file. I have granted permission to access the external storage.

i searched a bit on the internet and they suggested me to put this code in the manifest, but it didn't work for android 11

For my app I need values which are parsed by jSoup from a website and then returned to the user using a notification, these values change ~ every minute, so to be up-todate with the values I set up a task using a handler, this works good when the app is in foreground, but as soon as the user goes to the homescreen the app will return multiple exceptions like e.g. java.net.UnknownHostException or java.net.SocketTimeoutException, in the code this happens when jSoup is connecting to the specified site, I already tried using Services and AsyncTasks instead of threads, but it was always the exact same problem, I also searched for people with similar experiences, but I guess my issue is quite specific.

This is the code for the handler:

I am trying to open a text file with the following code:

I am working on a project which has three WiFi modules "ESP8266-01" (they represent three servers) and I want to read from all of them at same time.
And i want to achieve that by running three clients each on on a separate Thread .
I created a special class for this purpose (called IMU1) and I run it on PC and it works fine but when I try to move this program to android it gives me this error when i press the button :

I previously used external storage to store specific data that I would like to share between my applications (without having any contentprovider "host"), by using WRITE_EXTERNAL_STORAGE.

Not a media file, it is more like an encoded string in it.

It does not seem to be possible anymore on Android 11, without requesting MANAGE_EXTERNAL_STORAGE.

But this permission will not be granted by Google to all applications, and will require to fill a form, like everry "restricted permissions" (READ_CALL_LOG, READ_SMS, ACCESS_FINE_LOCATION, etc...) See support.google.com/googleplay/android-developer/answer/9888170

Exemple : By having XX applications, each one could be the first one to write a file (the first app used by the user basically), and the 3 other applications would read this file when started.

Any idea on how this can be achieved on Android 11? BlobManager seems to be appropriate but documentation is terrible (I tried it without success: new BlobStoreManager read write on Android 11)

I tried to build AOSP using the following commands:

While running cargo build, I'm getting the following error:

I'm facing a problem with an http request done in HTTP.java.

On desktop all works fine (that request is not performed because it's necessary only on Android).

In Android all works without that http request.

After that that http request is made, all others fail after timeout with UnknownHostException error, as if they no longer have access to the internet connection, even if it is active. Also after minutes and after the onResume all http requests fail. Although the app cannot get an http response, the AdMob ad appears in my App, so I think that probably the connection works (or does the AdMob library cache some ads and show them when needed?).

Often, in these cases sometimes it works again:

• uninstalling and reinstalling the App from Android Studio
• closing the App, waiting some minutes and reopening it
• clearing App data from the device
• waiting an undefined amount of time

❗ After several attempts I discovered that as soon as the problem occurs, almost every time, if I activate the airplane mode and then disable it, the data connection is deactivated and then reactivated, and the App can immediately execute all subsequent http requests without having to do anything else on your device and without even having to reopen the application.

• tested with wifi on a 1GB fibra network: same error
• I checked the connection: it is stable, in wifi and also with SIM
• in the manifest there is the permission for using internet (otherwise it would never have worked)
• at the same time, the same App on desktop works perfectly and at the best speed, receiving http responses in less than 1 second, so the server isn't the problem
• I tested also with the url https://www.google.it: same error, the same url is reachable in the device via browser in less than 1 second
• as in the line .timeout(10000) I'm using a timeout of 10 seconds, the server has timeout set to 60 seconds
• checked the server SSL "quality" at https://www.ssllabs.com/ssltest: got "A" in "Overall Rating"
• done the SIM "reboot" directly with a Vodafone operator

I'm testing on a real device with a flat 4G connection and with wifi, with "NetGuard - no-root firewall" VPN App installed.

This VPN works very well with all the other apps and probably mine too, but I can't rule out that it's the problem, although I hardly think it is (I use it since years without problems).

There is something wrong in my code? Or at least, how can I know the exact cause of this error?

Thanks.

AndroidLauncher.java:

I'm messing arround with the reqwest library and wanted to try some examples with Rust Playground. I have taken one of the simplest examples from the web but it does not compile.

Please follow the link below and click Run:

https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=fb0e7911a018ddb927cb13debd34fff4

This is the compile error shown in console: