android - 无法通过 DataBinding 或 Android 扩展访问 View

Question

我无法通过 DataBinding 或 Android Extensions 更改 Views 的值，但它可以通过“传统方式”(findViewById)工作。此外，当我在没有安全调用运算符(operator)的情况下通过 Android Extensions 的方式尝试时，它会抛出 NPE。
HourlyFragment.kt

class HourlyFragment : Fragment() {

private lateinit var binding: FragmentHourlyBinding

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                          savedInstanceState: Bundle?): View? {

    var rootView = inflater.inflate(R.layout.fragment_hourly, container, false)

    binding = DataBindingUtil.inflate(
        inflater, R.layout.fragment_hourly, container, false
    )

    // doesn't work
    //binding.tvHourly.text = "HOURLY!"

    val tvHourly : TextView = rootView.findViewById(R.id.tv_hourly)
    tvHourly.setText("HOURLY!!")

    // doesn't work, without safe call operator throws NullPointerException
    //tv_hourly?.text = "HOURLY!!!"

    return rootView
}

}
fragment_hourly.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".fragments.HourlyFragment">


        <TextView
            android:id="@+id/tv_hourly"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:text="hourly fragment" />

    </FrameLayout>
</layout>

Answer 1

目前您正在夸大您的观点两次，这导致了我认为的所有问题，因此只需夸大您的观点一次，看看它是否能解决您的问题
尝试以下

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                          savedInstanceState: Bundle?): View? {

 // var rootView = inflater.inflate(R.layout.fragment_hourly, container, false)

    binding = DataBindingUtil.inflate(
        inflater, R.layout.fragment_hourly, container, false
    )

    binding.tvHourly.text = "HOURLY!"

   // val tvHourly : TextView = rootView.findViewById(R.id.tv_hourly)
    tvHourly.setText("HOURLY!!")

   

    return binding.root
}