Hi everyone, I’m sorry if this has been discussed already somewhere. I’m trying to get the benefit o...

# detekt

[thuytrinh]

Hi everyone, I’m sorry if this has been discussed already somewhere. I’m trying to get the benefit of the ThrowsCount rule. I have a violated code here:

private fun ensureScanningIsPossible() {
    if (!isDiscoveryPermissionGranted) {
        throw DiscoveryErrors.DiscoveryPermissionsMissingError(neededDiscoveryPermissions)
    } else if (isDiscoveryOngoing) {
        throw DiscoveryErrors.DiscoveryAlreadyStarted
    } else if (!isBluetoothAvailable()) {
        throw DiscoveryErrors.BluetoothDisabledError
    } // More to come later...
}

Why is this discouraged? The doc said: “Functions should have clear throw statements”. How can we achieve a “clear” version? I tried to refactor by using nullable type but I feel a bit skeptical about the new code:

private fun ensureScanningIsPossible() {
    val error: DiscoveryErrors? = when {
        !isDiscoveryPermissionGranted -> DiscoveryErrors.DiscoveryPermissionsMissingError(neededDiscoveryPermissions)
        isDiscoveryOngoing -> DiscoveryErrors.DiscoveryAlreadyStarted
        !isBluetoothAvailable() -> DiscoveryErrors.BluetoothDisabledError
        else -> null
    }
    error?.let { throw it }
}

[gammax]

To give you a general answer, exceptions are generally discouraged in Kotlin.

This goes along with the ThrowsCount rule that should limit the usages of the throw keyword (and so reducing usages of exceptions).

In your specific case, the first snippet you posted is definitely better than the second and you should probably just suppress the rule violation for your function.

[gammax]

Or you can raise the ThrowsCount threshold a bit

[Venkat , Bangalore , India]

@thuytrinh can u paste ur detekt config ThrowsCount here

[Venkat , Bangalore , India]

ThrowsCount:
  active: true
  max: 2

[Venkat , Bangalore , India]

something like this

[Venkat , Bangalore , India]

i believe the ThrowsCount is activated

[thuytrinh]

That’s the exact config I’m using. The default one.

[Venkat , Bangalore , India]

just to reproduce ur issue i added like below and detekt found this

[Venkat , Bangalore , India]

private fun ensureScanningIsPossible() {
    if (!false) {
        throw NullPointerException()
    } else if (true) {
        throw throw NullPointerException()
    } else if (!false) {
        throw throw NullPointerException()
    } // More to come later...
}

[thuytrinh]

i believe the ThrowsCount is activated

Right. I’m aware of it. Just wanna understand the benefit of it as well as how to refactor

[Venkat , Bangalore , India]

style - 10min debt
ThrowsCount - [ensureScanningIsPossible] at

[Venkat , Bangalore , India]

@thuytrinh got ur point.. misunderstood mate

[Venkat , Bangalore , India]

@thuytrinh irrespective of throwcount over here, this style of more if/else leads to Codesmell:Switch https://refactoring.guru/smells/switch-statements