Hello guys Please help me with Coroutines I need to implemen

Question

Hello guys Please help me with Coroutines I need to implement this 1 Run my task in background mode 2 Stop the task in 30 seconds 3 Delay 10 seconds 4 Repeat my cycle 1 3 points infinitely <https prntscr com mu5xin> detailed on a picture

gildor · Answer

Oleh Ponomarenko · Answer

Here is my code ``` CoroutineScope Dispatchers Default launch BluetoothAdapter getDefaultAdapter takeIf it isEnabled enable if bluetoothScanner == null delay 3000 bluetoothScanner = BluetoothAdapter getDefaultAdapter bluetoothLeScanner try bluetoothScanner startScan filters settings callback catch e IllegalStateException Log e TAG e localizedMessage ``` Can you help to implement this due to my picture I need to scan for 30 seconds then stop for 10 seconds then resume to scanning for 30 seconds This cycle should be endless

gildor · Answer

To make it endless just wrap it to while true

Oleh Ponomarenko · Answer

How can I stop my task in 30 seconds

gildor · Answer

See my first comment

gildor · Answer

Use withTimeout and wrap it to try catch to catch cancellation exception this is probably the easiest way but you can check implementation and write own similar coroutine builder that doesn t throw exception on timeout

gildor · Answer

It also depends on how this scanning works

gildor · Answer

I see that you just start it and pass callback in this case you probably have some stopScanning method

Oleh Ponomarenko · Answer

yes i have

gildor · Answer

So just use delay 30 Seconds after start

Oleh Ponomarenko · Answer

Is it correct way ``` CoroutineScope Dispatchers Default launch while true val timeout = 20000L try Log d TAG starting bluetoothScanner startScan filters settings callback withTimeout timeout Log d TAG stop scan bluetoothScanner stopScan callback delay 10000 Log d TAG Pause works fine catch e Exception Log e TAG e localizedMessage ```

gildor · Answer

You don t need withTimeout in this case

gildor · Answer

Delay is enough

gildor · Answer

withTimeout make sense only if you have some suspend operation that should be cancelled on timeout in this case you just call non suspend method

gildor · Answer

Just a note about your code explicitly passing default dispatcher is most probably redundant

gildor · Answer

Just want to add that correctness of this code highly depends on how bluetoothScanner works but if it common call back API this approach should work

Oleh Ponomarenko · Answer

Everything works fine thanks

sitepodmatt · Answer

if bluetooth scanner becomes null which you seem to suggest is possible it will just continue looping

bdawg.io · Answer

Something to note is that `withTimeout` is collaborative cancellation If `stopScan` is a blocking method that takes 25 seconds it won t be cancelled at the 20 second timeout

Oleh Ponomarenko · Answer

Yes sometimes I use cancellation when I switch between running in Service and usual mode

gildor · Answer

this method doesn t look as blocking because callback is passed to startScan and to stopScan most probably it s some non blocking method that returns immediately