error: [kapt] An exception occurred: android.databinding.tool.util.LoggedErrorException: Found data binding error(s):? - kotlin

Question

I am learning databinding with mvvm but I am getting following errors I did not know what is the main problem.
DataBinderMapperImpl.java:9: error: cannot find symbol
import gahfy.net.databinding.ActivityPostListBindingImpl;
^
symbol: class ActivityPostListBindingImpl
location: package gahfy.net.databinding
error: [kapt] An exception occurred: android.databinding.tool.util.LoggedErrorException: Found data binding error(s):
[databinding] {"msg":"cannot find method getLoadingVisibility() in class gahfy.net.ui.post.PostListViewModel","file":"C:\\Users\\Edgar\\Documents\\MVVMPosts\\app\\src\\main\\res\\layout\\activity_post_list.xml","pos":[{"line0":22,"col0":37,"line1":22,"col1":68}]}
error: cannot find symbol
import gahfy.net.databinding.ActivityPostListBindingImpl;
^
symbol: class ActivityPostListBindingImpl
location: package gahfy.net.databinding
cannot find method getLoadingVisibility() in class gahfy.net.ui.post.PostListViewModel
what I have tried invalidate cache restart and rebuild and clean project it did not helped at all
below activity_post_list.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="viewModel"
type="gahfy.net.ui.post.PostListViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ProgressBar
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:mutableVisibility="#{viewModel.getLoadingVisibility()}" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/post_list"
android:layout_width="0dp"
android:layout_height="0dp"
app:adapter="#{viewModel.getPostListAdapter()}"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
below PostListActivity.kt
import android.os.Bundle
import androidx.annotation.StringRes
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProviders
import androidx.recyclerview.widget.LinearLayoutManager
import gahfy.net.R
import com.google.android.material.snackbar.Snackbar;
import gahfy.net.databinding.ActivityPostListBinding
class PostListActivity: AppCompatActivity() {
private lateinit var binding: ActivityPostListBinding
private lateinit var viewModel: PostListViewModel
private var errorSnackbar: Snackbar? = null
override fun onCreate(savedInstanceState: Bundle?){
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.activity_post_list)
binding.postList.layoutManager = LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false)
viewModel = ViewModelProviders.of(this).get(PostListViewModel::class.java)
viewModel.errorMessage.observe(this, Observer {
errorMessage -> if(errorMessage != null) showError(errorMessage) else hideError()
})
binding.viewModel = viewModel
}
private fun showError(#StringRes errorMessage:Int){
errorSnackbar = Snackbar.make(binding.root, errorMessage, Snackbar.LENGTH_INDEFINITE)
errorSnackbar?.setAction(R.string.retry, viewModel.errorClickListener)
errorSnackbar?.show()
}
private fun hideError(){
errorSnackbar?.dismiss()
}
}
below PostListViewModel.kt
class PostListViewModel:BaseViewModel(){
#Inject
lateinit var postApi: PostApi
private val loadingVisibility: MutableLiveData<Int> = MutableLiveData()
val errorMessage:MutableLiveData<Int> = MutableLiveData()
val errorClickListener = View.OnClickListener { loadPosts() }
private val postListAdapter: PostListAdapter = PostListAdapter()
private lateinit var subscription: Disposable
init{
loadPosts()
}
private fun loadPosts(){
subscription = postApi.getPosts()
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.doOnSubscribe { onRetrievePostListStart() }
.doOnTerminate { onRetrievePostListFinish() }
.subscribe(
// Add result
{ result -> onRetrievePostListSuccess(result) },
{ onRetrievePostListError() }
)
}
private fun onRetrievePostListStart(){
loadingVisibility.value = View.VISIBLE
errorMessage.value = null
}
private fun onRetrievePostListFinish(){
loadingVisibility.value = View.GONE
}
private fun onRetrievePostListSuccess(postList:List<Post>){
postListAdapter.updatePostList(postList)
}
private fun onRetrievePostListError(){
errorMessage.value = R.string.post_error
}
override fun onCleared() {
super.onCleared()
subscription.dispose()
}
}
below BindingAdapters.kt
#BindingAdapter("mutableText")
fun setMutableText(view: TextView, text: MutableLiveData<String>?) {
val parentActivity:AppCompatActivity? = view.getParentActivity()
if(parentActivity != null && text != null) {
text.observe(parentActivity, Observer { value -> view.text = value?:""})
}
#BindingAdapter("mutableVisibility")
fun setMutableVisibility(view: View, visibility: MutableLiveData<Int>?) {
val parentActivity:AppCompatActivity? = view.getParentActivity()
if(parentActivity != null && visibility != null) {
visibility.observe(parentActivity, Observer { value -> view.visibility = value?:View.VISIBLE})
}
}
#BindingAdapter("adapter")
fun setAdapter(view: RecyclerView, adapter: RecyclerView.Adapter<*>) {
view.adapter = adapter
}
}

Answer 1

It's about your databinding usage in xml.
1.Your used variable must be public or a have public getter.
2.If you want use public variable just use it name (without get).
So you must make this changes in this lines.
private val loadingVisibility: MutableLiveData<Int> = MutableLiveData()
private val postListAdapter: PostListAdapter = PostListAdapter()
To
val loadingVisibility: MutableLiveData<Int> = MutableLiveData()
val postListAdapter: PostListAdapter = PostListAdapter()
And
app:mutableVisibility="#{viewModel.getLoadingVisibility()}"
app:adapter="#{viewModel.getPostListAdapter()}"
To
app:mutableVisibility="#{viewModel.loadingVisibility}"
app:adapter="#{viewModel.postListAdapter}"
BindAdapters
class BindAdapters {
companion object {
#BindingAdapter("mutableText")
fun setMutableText(view: TextView, text: MutableLiveData<String>?) {
val parentActivity: AppCompatActivity? = view.getParentActivity()
if (parentActivity != null && text != null) {
text.observe(parentActivity, Observer { value -> view.text = value ?: "" })
}
}
#BindingAdapter("mutableVisibility")
fun setMutableVisibility(view: View, visibility: MutableLiveData<Int>?) {
val parentActivity: AppCompatActivity? = view.getParentActivity()
if (parentActivity != null && visibility != null) {
visibility.observe(
parentActivity,
Observer { value -> view.visibility = value ?: View.VISIBLE })
}
}
#BindingAdapter("adapter")
fun setAdapter(view: RecyclerView, adapter: RecyclerView.Adapter<*>) {
view.adapter = adapter
}
}
}