I HATE Android
First I have to figure out why my device is not recognized by adb.
Then I have to figure out why my app keeps crashing after I redeploy it after changing some code. Turns out it's android 11's optimization causing the problem. Disable it fixed the issue.
Then the logcat is not working. The ADB is fine, but just logcat showing the device offline. I cannot read any log from my code and I can only know what's going wrong by triggering the exception multiple times and hoping the system will show me the stacktrace.
And to make things worse, the json naming annotation stopped working. I told it the requestId field should be request_id in json but it just doesn't care. I literally make no change to the code, just copy and paste from the old one. WTF
Being rejected by HRs on job finding app is not that worse.
But writing android makes me want to die.
@skyblond It should be possible to pipe raw data into the input. The output should be okay.
@AmpBenzScientist The emulator from Google is not support bluetooth, said by documents. The camera on my laptop is crap and can't recognize any barcode 
@skyblond That's surprising.
@AmpBenzScientist Emulator is still a thing, but my app uses camera to scan barcode and Bluetooth to send data to thermal printer. Emulator can't achieve that...