android - 只有安全或非 null asserted kotlin 消息

Question

我正在尝试在我的手机上运行一个应用程序，但我的项目一直遇到这个问题请帮助我解决这个问题谢谢Only safe or non null asserted calls are allowed on a nullable receiver type of arraylis

register_btn.setOnClickListener { val email = 
email_registersscreen.text.toString()
   val password = password_registerscreeb.text.toString()

   Log.d("MainActiviy", "Email is:" + email)
   Log.d("MainActivity", "Password:$password")

   //Firebase Authentication  user  with email and password

   FirebaseAuth.getInstance().createUserWithEmailAndPassword(email, password)
       .addOnCompleteListener {
           if (!it.isSuccessful) return@addOnCompleteListener

           // else it successful
           Log.d("Main", "successfully created user with uid: 
${it.result.user.uid}")

           }
   }

Answer 1

此问题与 Kotlin 中的空安全有关。因为我真的看不到你的代码中的 arrayList 在哪里，我假设你有错误${it.result.user.uid} 它应该类似于 ${it.result?.user?.uid}

您可以在这里阅读更多相关信息:https://kotlinlang.org/docs/reference/null-safety.html