Fragment绑定失败?

#54 · closed · 2 comments

aheven

**版本号**：2.0.5 Fragment绑定失败？原始代码为： ```kotlin  <androidx.fragment.app.FragmentContainerView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/fragment_container" android:layout_width="match_parent" android:layout_height="match_parent" android:name="**.main.MainFragment" android:fitsSystemWindows="true"/>  class MainFragment : Fragment() { private val binding:FragmentMainBinding by binding() override fun onViewCreated(view: View, savedInstanceState: Bundle?) { super.onViewCreated(view, savedInstanceState) binding.content.text = "123456" } } ``` 但是在页面中，MainFragment的布局无法加载出来。查看源码，发现并没有将View绑定至Fragment的相关代码： ```kotlin class FragmentBindingProperty<VB : ViewBinding>(private val clazz: Class<VB>) : ReadOnlyProperty<Fragment, VB> { override fun getValue(thisRef: Fragment, property: KProperty<*>): VB = requireNotNull(thisRef.view) { "The property of ${property.name} has been destroyed." } .getBinding(clazz).also { binding -> if (binding is ViewDataBinding) binding.lifecycleOwner = thisRef.viewLifecycleOwner } } ``` 是否和这个有关系？

Comments

aheven

看到示例，`Fragment` 构造传递了资源 ID，所以是通过这种方式初始化的。因此 `by binding()` 的作用仅为绑定 `Fragment` 视图。对于 Androidx 低版本，例如，`AppCompatDialogFragment` 在 `androidx.appcompat 1.4.0` 之前未添加 ResourceId 构造参数，`AppCompatActivity` 在 `androidx.appcompat 1.1.0` 之前未添加 ResourceId 构造参数。建议添加 View 为空的时候抛出异常提示将 View 添加到 Fragment。

DylanCaiCoding

感谢反馈，已将异常提示改为 `The constructor missing layout id or the property of ${property.name} has been destroyed.`。 DialogFragment 是推荐下面这么来用，binding 写在 Dialog 里。 ```kotlin class LoadingDialogFragment(private val text: String? = null) : DialogFragment() { override fun onCreateDialog(savedInstanceState: Bundle?): Dialog { isCancelable = false return LoadingDialog(requireContext()) } inner class LoadingDialog(context: Context) : Dialog(context, R.style.DialogTheme) { private val binding: DialogLoadingBinding by binding() override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) window?.setLayout(MATCH_PARENT, WRAP_CONTENT) binding.tvMessage.text = "Wait a minute..." } } } ```