How to properly handle an error with try-catch-CodePudding

My app keeps crashing with FirebaseNetworkException whenever I don't have an internet connection even though I'm handling the exception, am I missing something?:

fun getToken(): String? {
        val token = StringBuilder()
        val countDownLatch = CountDownLatch(1)
        try {


            FirebaseAuth.getInstance().currentUser?.getIdToken(false)
                ?.addOnCompleteListener { task ->
                    token.append(task.result?.token)
                    println(task.result?.token)
                    countDownLatch.countDown()
                }
            return try {
                countDownLatch.await(30L, TimeUnit.SECONDS)
                token.toString()
            } catch (ie: InterruptedException) {
                null
            }
        }
        catch (exception: FirebaseNetworkException)

        {
            println("exception is ${exception.message.toString()}")
            return null;
        }
    }

This the error returned:

 Caused by: com.google.firebase.FirebaseNetworkException: A network error (such as timeout, interrupted connection or unreachable host) has occurred.

CodePudding user response：

Firebase has provided a method to whether response is success or failure. Reference link.

Returns true if the Task has completed successfully; false otherwise.

if(task.isSuccessful) {}

Also, you can use a callback method to return token, I have make it a more easy for you. In your onCreate()

getToken { token ->
    println("Your token $token")
}

Initialize a function with a callback listener

fun getToken(callback: (token: String?) -> Unit) {

FirebaseAuth.getInstance().currentUser?.getIdToken(false)?.addOnCompleteListener { task ->
        if (task.isSuccessful) {
            callback.invoke(task.result.token)
        } else
            callback.invoke(null)
    }
}