Extracted ViewHolder into a separate class

app/src/main/java/com/paktalin/vocabularynotebook/Holder.kt

+package com.paktalin.vocabularynotebook
+
+import android.support.v7.widget.RecyclerView
+import android.view.View
+import android.widget.LinearLayout
+import android.widget.TextView
+import com.paktalin.vocabularynotebook.firestoreitems.WordItem
+import kotlinx.android.synthetic.main.word_item.view.*
+
+class Holder(itemView: View) : RecyclerView.ViewHolder(itemView) {
+    private val tvWord: TextView = itemView.word
+    private val tvTranslation: TextView = itemView.translation
+    val layout: LinearLayout = itemView.layout
+
+    fun init(wordItem: WordItem, position: Int, showPopupMenu: (View, Int) -> Unit) {
+        tvWord.text = wordItem.pojo.word
+        tvTranslation.text = wordItem.pojo.translation
+        itemView.setOnClickListener { showPopupMenu(itemView, position) }
+    }
+}

app/src/main/java/com/paktalin/vocabularynotebook/VocabularyAdapter.kt

@@ -14,7 +14,7 @@ import com.paktalin.vocabularynotebook.ui.activities.MainActivity
 import com.paktalin.vocabularynotebook.utils.addFragment
 import kotlinx.android.synthetic.main.word_item.view.*
 
-class VocabularyAdapter(private val fullVocabulary: Vocabulary, private val mainActivity: MainActivity) : RecyclerView.Adapter<VocabularyAdapter.ViewHolder>() {
+class VocabularyAdapter(private val fullVocabulary: Vocabulary, private val mainActivity: MainActivity) : RecyclerView.Adapter<Holder>() {
 
     private var displayedVocabulary = Vocabulary(fullVocabulary)
     private lateinit var recyclerView: RecyclerView
@@ -30,33 +30,30 @@ class VocabularyAdapter(private val fullVocabulary: Vocabulary, private val main
         mainActivity.searchView.setOnQueryTextListener(OnQueryTextListener(this@VocabularyAdapter))
     }
 
-    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
-        val view = LayoutInflater.from(parent.context)
-                .inflate(R.layout.word_item, parent, false)
-        return ViewHolder(view)
-    }
-
-    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
-        val wordItem = displayedVocabulary.getAt(position)
-        holder.tvWord.text = wordItem.pojo.word
-        holder.tvTranslation.text = wordItem.pojo.translation
-        holder.itemView.setOnClickListener { showPopupMenu(holder.itemView, position) }
-        //todo set click listener to menu
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): Holder {
+        val view = LayoutInflater.from(parent.context).inflate(R.layout.word_item, parent, false)
+        return Holder(view)
     }
 
     override fun getItemCount(): Int {
         return displayedVocabulary.size()
     }
 
+    override fun onBindViewHolder(holder: Holder, position: Int) {
+        val wordItem = displayedVocabulary.getAt(position)
+        holder.init(wordItem, position) { view, p -> showPopupMenu(view, p)}
+        //todo set click listener to menu
+    }
+
     private fun showPopupMenu(v: View, position: Int) {
         val popup = PopupMenu(mainActivity, v)
-        val inflater = popup.menuInflater
-        inflater.inflate(R.menu.word_item_menu, popup.menu)
+        popup.menuInflater.inflate(R.menu.word_item_menu, popup.menu)
         popup.setOnMenuItemClickListener {
             if (it.itemId == R.id.option_delete) { deleteWord(position) }
             if (it.itemId == R.id.option_edit) { startEditFragment(v, displayedVocabulary.getAt(position)) }
             true
         }
+        // if not edit mode, then start EditFragment
         if (mainActivity.supportFragmentManager.findFragmentByTag("edit_fragment") == null)
             popup.show()
     }
@@ -105,12 +102,6 @@ class VocabularyAdapter(private val fullVocabulary: Vocabulary, private val main
         addFragment(mainActivity.supportFragmentManager, EditWordFragment(), container.id, arguments, "edit_fragment")
     }
 
-    inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
-        val tvWord: TextView = itemView.word
-        val tvTranslation: TextView = itemView.translation
-        val layout: LinearLayout = itemView.layout
-    }
-
     fun filter(query: String) {
         displayedVocabulary.clear()
         if (query.isEmpty())