我想使用ArrayAdapter中的字符串数组初始化counties，但是运行应用程序时出现错误消息。这是我的代码:
class EnglandFragment : Fragment() {
// Access a Cloud Firestore instance from your Activity
val db = FirebaseFirestore.getInstance()
lateinit var adapter : ArrayAdapter<String>
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val root = inflater.inflate(R.layout.fragment_england, container, false)
var mContext: Context? = null
mContext = getActivity() as CountriesActivity
mContext.initializeCustomActionBar(R.drawable.england_flag, R.string.title_counties)
var counties : Array<String>
val docRef = db.collection("UKSites").document("England")
docRef.get()
.addOnSuccessListener { document ->
if (document != null) {
counties = document.get("Counties") as Array<String>
adapter = ArrayAdapter(this, android.R.layout.simple_list_item_1, counties)
} else {
Log.d("Debug", "No such document")
}
}
.addOnFailureListener { exception ->
Log.d("Debug", "get failed with ", exception)
}
return root
}
}
我收到以下错误消息:
None of the following functions can be called with the arguments supplied:
public constructor ArrayAdapter<T : Any!>(@NonNull p0: Context, p1: Int, @NonNull p2: Array<(out) String!>) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@NonNull p0: Context, p1: Int, p2: Int) defined in android.widget.ArrayAdapter
public constructor ArrayAdapter<T : Any!>(@NonNull p0: Context, p1: Int, @NonNull p2: (Mutable)List<String!>) defined in android.widget.ArrayAdapter
最佳答案
似乎您的代码未提供正确的参数，如果您使用的是androidx.fragment.app.Fragment，则可以简单地调用requireContext()和requireActivity()
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val root = inflater.inflate(R.layout.fragment_england, container, false)
(requireActivity() as CountriesActivity).initializeCustomActionBar(R.drawable.england_flag, R.string.title_counties)
val docRef = db.collection("UKSites").document("England")
docRef.get()
.addOnSuccessListener { document ->
if (document != null) {
val counties = document.get("Counties") as Array<String>
adapter = ArrayAdapter(requireContext(), android.R.layout.simple_list_item_1, counties)
} else {
Log.d("Debug", "No such document")
}
}
.addOnFailureListener { exception ->
Log.d("Debug", "get failed with ", exception)
}
return root
}
仅供参考，这是从
Fragment-> Activity强制转换和/或调用方法的非常不好的做法(requireActivity() as CountriesActivity).initializeCustomActionBar(R.drawable.england_flag, R.string.title_counties)
您应该在 Activity 上添加
initializeCustomActionBar或使其实现一个片段可以随后调用的接口(interface)(通过构造函数)。但是我不会太担心，因为它超出了您的问题范围。