调用 Fragment 构造函数导致异常，kotlin?答案

【问题标题】：calling Fragment constructor caused an exception, kotlin?调用 Fragment 构造函数导致异常，kotlin?
【发布时间】：2020-09-22 09:26:06
【问题描述】：

我正在使用navigationcontroller 导航到另一个片段

导航到第二个片段

private fun moveToNextScreen(userId: String) {
    val bundle = bundleOf("userId" to userId)
    binding.googleLogin.findNavController().navigate(
        R.id.action_loginFragment_to_signupFragment, bundle
    )
}

我正在导航到的片段

class UserSetupFragment : Fragment() {
private lateinit var binding: FragmentUserSetupBinding

var optionCb = mutableListOf<AppCompatCheckBox>()
var optionsList =
    ArrayList<String>(Arrays.asList(*resources.getStringArray(R.array.profile_options)))

override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    // Inflate the layout for this fragment
    binding = FragmentUserSetupBinding.inflate(inflater, container, false)
    return binding.getRoot()
}

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    createOptionsCheckBox()
}

private fun createOptionsCheckBox() {
    for (option in optionsList) {
        val checkBox = AppCompatCheckBox(activity)
        checkBox.setText(option)
        checkBox.setTextColor(ContextCompat.getColor(requireActivity(), android.R.color.black));
        optionCb.add(checkBox)
        binding.optionsLayout.addView(checkBox)
    }
}

}

我遇到了异常

java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=66957, result=-1, data=Intent { (has extras) }} to activity {com.patient.reach52/com.patient.reach52.view.authenticate.AuthenticateActivity}: androidx.fragment.app.Fragment$InstantiationException: Unable to instantiate fragment com.patient.reach52.view.authenticate.UserSetupFragment: calling Fragment constructor caused an exception

这里怎么了？

【问题讨论】：

标签： android kotlin navigation fragment

【解决方案1】：

在片段附加到活动之前，您无法访问resources。所以你必须延迟optionsList的实例化

class UserSetupFragment : Fragment() {
    lateinit var optionsList: List<String>

    override fun onAttach(context: Context) {
        super.onAttach(context)
        optionsList = resources.getStringArray(R.array.profile_options).toList()
    }
...

【讨论】：

【解决方案2】：

您无法从 FragmentClass 访问资源。您应该在 onCreateView 或 onCreate 中定义任何您想要的内容。

例子：

class ExampleFragment : Fragment(){

     private lateinit var example : String

}
    override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View {
    _binding = FragmentExampleBinding.inflate(inflater, container, false)
    val view = binding.root

    example = resources.getString(R.string.random)
    
    return view
}

【讨论】：