title: viewBinding is not working with error (Android studio 4)
body: <p>I make android application with kotlin by Android studio 4 (4.11).</p>
  <p>findViewById is deprecated in Androd Studio 4 ,then I use viewBinding.
  <a href="https://developer.android.com/topic/libraries/view-binding" rel="noreferrer">https://developer.android.com/topic/libraries/view-binding</a></p>
  <p>But viewBinding is not working with error.</p>
  <pre><code>(path)/MainActivity.kt: (6, 31): Unresolved reference: ActivityMainBinding
  </code></pre>
  <p>Can someone tell me the reason for the error or my mistake?</p>
  <p>code is below.</p>
  <p>build.grade:</p>
  <pre><code>  android {
    ...
  // &lt;-- added
      buildFeatures {
          viewBinding = true
      }
  // --&gt;
    }
  </code></pre>
  <p>res/layout/activity_main.xml:</p>
  <pre><code>&lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
  &lt;androidx.constraintlayout.widget.ConstraintLayout xmlns:android=&quot;http://schemas.android.com/apk/res/android&quot;
      xmlns:app=&quot;http://schemas.android.com/apk/res-auto&quot;
      xmlns:tools=&quot;http://schemas.android.com/tools&quot;
      android:layout_width=&quot;match_parent&quot;
      android:layout_height=&quot;match_parent&quot;
      tools:context=&quot;.MainActivity&quot;&gt;
  
      &lt;TextView
          android:id=&quot;@+id/viewText&quot; // added.
          android:layout_width=&quot;wrap_content&quot;
          android:layout_height=&quot;wrap_content&quot;
          android:text=&quot;Hello World!&quot;
          app:layout_constraintBottom_toBottomOf=&quot;parent&quot;
          app:layout_constraintLeft_toLeftOf=&quot;parent&quot;
          app:layout_constraintRight_toRightOf=&quot;parent&quot;
          app:layout_constraintTop_toTopOf=&quot;parent&quot; /&gt;
  
  &lt;/androidx.constraintlayout.widget.ConstraintLayout&gt;
  </code></pre>
  <pre><code>package com.example.myapplication
  
  import androidx.appcompat.app.AppCompatActivity
  import android.os.Bundle
  
  private lateinit var binding: ActivityMainBinding // added. &lt;== error (6:31)
  
  class MainActivity : AppCompatActivity() {
      override fun onCreate(savedInstanceState: Bundle?) {
          super.onCreate(savedInstanceState)
  
  // &lt;-- added.
          binding = ActivityMainBinding.inflate(layoutInflater)
          val view = binding.root
          binding.textView.text = &quot;Test view binding.&quot;
  // --&gt;
  
          setContentView(R.layout.activity_main)
      }
  }
  </code></pre>