Fix part of #632 : Replace current recyclerview implementation with BindableAdapter usage in Help Activity

app/src/main/java/org/oppia/app/help/HelpFragmentPresenter.kt

@@ -6,42 +6,48 @@ import android.view.ViewGroup
 import androidx.appcompat.app.AppCompatActivity
 import androidx.fragment.app.Fragment
 import androidx.recyclerview.widget.LinearLayoutManager
-import org.oppia.app.R
 import org.oppia.app.databinding.HelpFragmentBinding
+import org.oppia.app.databinding.HelpItemBinding
 import org.oppia.app.fragment.FragmentScope
+import org.oppia.app.recyclerview.BindableAdapter
+import org.oppia.app.viewmodel.ViewModelProvider
 import javax.inject.Inject
 
 /** The presenter for [HelpFragment]. */
 @FragmentScope
 class HelpFragmentPresenter @Inject constructor(
   private val activity: AppCompatActivity,
-  private val fragment: Fragment
+  private val fragment: Fragment,
+  private val viewModelProvider: ViewModelProvider<HelpListViewModel>
 ) {
-  private val arrayList = ArrayList<HelpViewModel>()
+  private lateinit var binding: HelpFragmentBinding
 
   fun handleCreateView(inflater: LayoutInflater, container: ViewGroup?): View? {
-    val binding: HelpFragmentBinding =
-      HelpFragmentBinding.inflate(
-        inflater,
-        container,
-        /* attachToRoot= */ false
-      )
-    binding.lifecycleOwner = fragment
+    val viewModel = getHelpListViewModel()
+
+    binding = HelpFragmentBinding.inflate(inflater, container, /* attachToRoot = */ false)
     binding.helpFragmentRecyclerView.apply {
-      adapter = HelpCategoryAdapter(activity, getRecyclerViewItemList())
-      layoutManager = LinearLayoutManager(activity)
+      layoutManager = LinearLayoutManager(activity.applicationContext)
+      adapter = createRecyclerViewAdapter()
+    }
+
+    binding.let {
+      it.lifecycleOwner = fragment
+      it.viewModel = viewModel
     }
     return binding.root
   }
 
-  private fun getRecyclerViewItemList(): ArrayList<HelpViewModel> {
-    for (item in HelpItems.values()) {
-      if (item == HelpItems.FAQ) {
-        val category1 = fragment.getString(R.string.frequently_asked_questions_FAQ)
-        val helpViewModel = HelpViewModel(category1)
-        arrayList.add(helpViewModel)
-      }
-    }
-    return arrayList
+  private fun createRecyclerViewAdapter(): BindableAdapter<HelpItemViewModel> {
+    return BindableAdapter.SingleTypeBuilder
+      .newBuilder<HelpItemViewModel>()
+      .registerViewDataBinderWithSameModelType(
+        inflateDataBinding = HelpItemBinding::inflate,
+        setViewModel = HelpItemBinding::setViewModel
+      ).build()
+  }
+
+  private fun getHelpListViewModel(): HelpListViewModel {
+    return viewModelProvider.getForFragment(fragment, HelpListViewModel::class.java)
   }
 }

app/src/main/java/org/oppia/app/help/HelpItemViewModel.kt

@@ -0,0 +1,18 @@
+package org.oppia.app.help
+
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.ViewModel
+import org.oppia.app.R
+
+/** [ViewModel] for the recycler view of HelpActivity. */
+class HelpItemViewModel(
+  val activity: AppCompatActivity,
+  val title: String
+) : ViewModel() {
+  fun onClick(title: String) {
+    if (title == activity.getString(R.string.frequently_asked_questions_FAQ)) {
+      val routeToFAQListener = activity as RouteToFAQListListener
+      routeToFAQListener.onRouteToFAQList()
+    }
+  }
+}

app/src/main/java/org/oppia/app/help/HelpListViewModel.kt

@@ -0,0 +1,28 @@
+package org.oppia.app.help
+
+import androidx.appcompat.app.AppCompatActivity
+import androidx.lifecycle.ViewModel
+import org.oppia.app.R
+import javax.inject.Inject
+
+/** View model in [HelpFragment]. */
+class HelpListViewModel @Inject constructor(
+  val activity: AppCompatActivity
+) : ViewModel() {
+  private val arrayList = ArrayList<HelpItemViewModel>()
+
+  val helpItemItemList: List<HelpItemViewModel> by lazy {
+    getRecyclerViewItemList()
+  }
+
+  private fun getRecyclerViewItemList(): ArrayList<HelpItemViewModel> {
+    for (item in HelpItems.values()) {
+      if (item == HelpItems.FAQ) {
+        val category1 = activity.getString(R.string.frequently_asked_questions_FAQ)
+        val helpViewModel = HelpItemViewModel(activity,category1)
+        arrayList.add(helpViewModel)
+      }
+    }
+    return arrayList
+  }
+}

app/src/main/res/layout-land/help_item.xml

@@ -6,7 +6,7 @@
 
     <variable
       name="viewModel"
-      type="org.oppia.app.help.HelpViewModel" />
+      type="org.oppia.app.help.HelpItemViewModel" />
   </data>
 
   <TextView
@@ -19,6 +19,7 @@
     android:paddingTop="20dp"
     android:paddingEnd="16dp"
     android:paddingBottom="20dp"
+    android:onClick="@{() -> viewModel.onClick(viewModel.title)}"
     android:text="@{viewModel.title}"
     android:textColor="@color/oppiaPrimaryText"
     android:textSize="16sp"

app/src/main/res/layout/help_fragment.xml

@@ -1,5 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
-<layout xmlns:android="http://schemas.android.com/apk/res/android">
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+  xmlns:app="http://schemas.android.com/apk/res-auto">
+
+  <data>
+
+    <variable
+      name="viewModel"
+      type="org.oppia.app.help.HelpListViewModel" />
+  </data>
 
   <androidx.constraintlayout.widget.ConstraintLayout
     android:layout_width="match_parent"
@@ -8,6 +16,7 @@
     <androidx.recyclerview.widget.RecyclerView
       android:id="@+id/help_fragment_recycler_view"
       android:layout_width="match_parent"
-      android:layout_height="match_parent" />
+      android:layout_height="match_parent"
+      app:list="@{viewModel.helpItemItemList}" />
   </androidx.constraintlayout.widget.ConstraintLayout>
 </layout>

app/src/main/res/layout/help_item.xml

@@ -6,7 +6,7 @@
 
     <variable
       name="viewModel"
-      type="org.oppia.app.help.HelpViewModel" />
+      type="org.oppia.app.help.HelpItemViewModel" />
   </data>
 
   <TextView
@@ -19,6 +19,7 @@
     android:paddingTop="20dp"
     android:paddingEnd="16dp"
     android:paddingBottom="20dp"
+    android:onClick="@{() -> viewModel.onClick(viewModel.title)}"
     android:text="@{viewModel.title}"
     android:textColor="@color/oppiaPrimaryText"
     android:textSize="16sp"