Words can be deleted by long press

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

@@ -9,9 +9,16 @@ import android.view.ViewGroup
 import android.widget.TextView
 import com.paktalin.vocabularynotebook.activities.WordItemInfoActivity
 
-class VocabularyAdapter(private val wordItems: List<WordItem>,
+class VocabularyAdapter(private val wordItems: MutableList<WordItem>,
                         private val context: Context) : RecyclerView.Adapter<VocabularyAdapter.ViewHolder>() {
 
+    private lateinit var recyclerView: RecyclerView
+
+    override fun onAttachedToRecyclerView(recyclerView: RecyclerView) {
+        super.onAttachedToRecyclerView(recyclerView)
+        this.recyclerView = recyclerView
+    }
+
     override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
         val view = LayoutInflater.from(parent.context)
                 .inflate(R.layout.word_item, parent, false)
@@ -23,6 +30,7 @@ class VocabularyAdapter(private val wordItems: List<WordItem>,
         holder.tvWord.text = wordItem.pojo.word
         holder.tvTranslation.text = wordItem.pojo.translation
         holder.itemView.setOnClickListener { openWordItemInfo(wordItem) }
+        holder.itemView.setOnLongClickListener { deleteWordItem(position);true }
     }
 
     override fun getItemCount(): Int {
@@ -40,5 +48,13 @@ class VocabularyAdapter(private val wordItems: List<WordItem>,
         context.startActivity(intentWordItemInfo)
     }
 
+    private fun deleteWordItem(position: Int) {
+        wordItems[position].delete()
+        wordItems.removeAt(position)
+        recyclerView.removeViewAt(position)
+        this.notifyItemRemoved(position)
+        this.notifyItemRangeChanged(position, wordItems.size)
+    }
+
     companion object { private val TAG = "VN/" + VocabularyAdapter::class.java.simpleName }
 }
\ No newline at end of file

app/src/main/java/com/paktalin/vocabularynotebook/WordItem.java

 package com.paktalin.vocabularynotebook;
 
+import android.support.annotation.NonNull;
+import android.util.Log;
+
+import com.google.android.gms.tasks.OnFailureListener;
+import com.google.android.gms.tasks.OnSuccessListener;
+import com.google.firebase.firestore.DocumentReference;
+import com.google.firebase.firestore.FirebaseFirestore;
+
 import java.io.Serializable;
 
 public class WordItem implements Serializable {
+    private static final String TAG = "VN/" + WordItem.class.getSimpleName();
+
     public static class WordItemPojo implements Serializable{
 
         private String word, translation;
@@ -30,13 +40,31 @@ public class WordItem implements Serializable {
     }
 
     private String id;
+    private String vocabularyId;
     private WordItemPojo pojo;
 
-    public WordItem(String word, String translation, String id) {
+    public WordItem(String word, String translation, String id, String vocabularyId) {
         this.pojo = new WordItemPojo(word, translation);
+        this.vocabularyId = vocabularyId;
         this.id = id;
     }
 
+    public void delete() {
+        FirebaseFirestore.getInstance().collection("vocabularies").document(vocabularyId)
+                .collection("words").document(id).delete()
+                .addOnSuccessListener(new OnSuccessListener<Void>() {
+            @Override
+            public void onSuccess(Void aVoid) {
+                Log.i(TAG, "Successfully deleted word with id " + id);
+            }
+        }).addOnFailureListener(new OnFailureListener() {
+            @Override
+            public void onFailure(@NonNull Exception e) {
+                Log.w(TAG, "deleteWordWithId " + id + ":failure", e.fillInStackTrace());
+            }
+        });
+    }
+
     public WordItemPojo getPojo() {
         return pojo;
     }

app/src/main/java/com/paktalin/vocabularynotebook/activities/VocabularyFragment.kt

@@ -87,8 +87,7 @@ class VocabularyFragment : Fragment() {
         for (ref in documents) {
             val word = ref.get("word").toString()
             val translation = ref.get("translation").toString()
-            val wordItemId = ref.id
-            wordItems.add(WordItem(word, translation, wordItemId))
+            wordItems.add(WordItem(word, translation, ref.id, vocabulary.id))
         }
 
         val adapter = VocabularyAdapter(wordItems, activity!!)