android - Kotlin 。未经检查将 : Any? 转换为 HashMap?

Question

我想得到 HashMap<String?, String?>?来自 firebaseDatabase :

override fun onDataChange(dataSnapshot: DataSnapshot) {
    val users: HashMap<String?, String?>? = dataSnapshot.value as HashMap<String?, String?>?  // todo !!!
    if (users != null) {
        if (!users.containsKey(userUid)) {
            users[userUid] = userName
        }
    }
}

此代码有效但 Android Studio在第二行显示警告:

 Unchecked cast: Any? to HashMap<String?, String?>?

如何以正确的方式解决这个问题？

Answer 1

GenericTypeIndicator 的方法有效，谢谢@leoderprofi

    val ti = object : GenericTypeIndicator<HashMap<String?, String?>?>() {}
    //...
    override fun onDataChange(dataSnapshot: DataSnapshot) {
        val users: HashMap<String?, String?>? = dataSnapshot.getValue(ti)
        if (users != null) {
            if (!users.containsKey(userUid)) {
                users[userUid] = userName
            }
        }
    }