如何正确地在 Kotlin 中快速失败？

Question

I want to fail fast if a specific function is returning null . I have no case where default value would make processing meaningful.

This is the snippet:

        val entityAttributes = entity.optJSONObject("Attributes") ?: run {
            LOG.error("Could not find 'Attribute' entry in Entity object")
            return
        }

So if entity.optJSONObject("Attributes") returns null (which it does desipite the opt* ) I want to escape from the function scope.

Is the way I did it the proper one? I am fairly new to Kotlin and want to get used to the proper ways of doing these things as early as possible.

Answer 1

You can return from the function early like you do above. If your function returns something besides Unit, then you'd have to return some default value.

Throwing an exception allows you to exit a function without returning anything, but the exception will crash the program if you don't catch it somewhere. Sometimes this is exactly what you want to happen if the error is something that should never happen, because then you'll catch it during testing and be able to fix it before releasing your application.

Use the global error(cause: Any) function and it will immediately throw an IllegalStateException.