Implementing live data in viewmodel

app/src/main/java/com/example/android/guesstheword/screens/game/GameFragment.kt

@@ -22,6 +22,7 @@ import android.view.View
 import android.view.ViewGroup
 import androidx.databinding.DataBindingUtil
 import androidx.fragment.app.Fragment
+import androidx.lifecycle.Observer
 import androidx.lifecycle.ViewModelProviders
 import androidx.navigation.fragment.NavHostFragment.findNavController
 import com.example.android.guesstheword.R
@@ -51,16 +52,26 @@ class GameFragment : Fragment() {
 
         binding.correctButton.setOnClickListener {
             viewModel.onCorrect()
-            updateScoreText()
-            updateWordText()
         }
         binding.skipButton.setOnClickListener {
             viewModel.onSkip()
-            updateScoreText()
-            updateWordText()
         }
-        updateScoreText()
+
-        updateWordText()
+        viewModel.score.observe(this, Observer {
+            binding.scoreText.text = it.toString()
+        })
+
+        viewModel.word.observe(this, Observer {
+            binding.wordText.text = it
+        })
+
+        viewModel.eventGameFinished.observe(this, Observer {
+            if (it) {
+                gameFinished()
+                viewModel.onGameFinishComplete()
+            }
+        })
+
         return binding.root
 
     }
@@ -69,18 +80,8 @@ class GameFragment : Fragment() {
      * Called when the game is finished
      */
     private fun gameFinished() {
-        val action = GameFragmentDirections.actionGameToScore(viewModel.score)
+        val action = GameFragmentDirections.actionGameToScore(viewModel.score.value ?: 0)
         findNavController(this).navigate(action)
     }
 
-    /** Methods for updating the UI **/
-
-    private fun updateWordText() {
-        binding.wordText.text = viewModel.word
-
-    }
-
-    private fun updateScoreText() {
-        binding.scoreText.text = viewModel.score.toString()
-    }
 }

app/src/main/java/com/example/android/guesstheword/screens/game/GameViewModel.kt

@@ -1,27 +1,33 @@
 package com.example.android.guesstheword.screens.game
 
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
-import timber.log.Timber
 
 class GameViewModel(): ViewModel() {
     // The current word
-    var word = ""
+    private val _word = MutableLiveData<String>()
+    val word: LiveData<String>
+        get() = _word
 
     // The current score
-    var score = 0
+    private val _score = MutableLiveData<Int>()
+    val score: LiveData<Int>
+        get() = _score
+
+    private val _eventGameFinished = MutableLiveData<Boolean>()
+    val eventGameFinished: LiveData<Boolean>
+        get() = _eventGameFinished
 
     // The list of words - the front of the list is the next word to guess
     private lateinit var wordList: MutableList<String>
 
     init {
-        Timber.i("GameViewModel created")
         resetList()
         nextWord()
-    }
+        _eventGameFinished.value = false
-
+        _word.value = ""
-    override fun onCleared() {
+        _score.value = 0
-        super.onCleared()
-        Timber.i("GameViewModel destroyed")
     }
 
     /**
@@ -60,19 +66,25 @@ class GameViewModel(): ViewModel() {
     private fun nextWord() {
         //Select and remove a word from the list
         if (wordList.isEmpty()) {
-//            gameFinished()
+            _eventGameFinished.value = true
         } else {
-            word = wordList.removeAt(0)
+            _word.value = wordList.removeAt(0)
         }
     }
 
     fun onSkip() {
-        score--
+        if (score.value != 0) {
+            _score.value = (score.value)?.dec()
+        }
         nextWord()
     }
 
     fun onCorrect() {
-        score++
+        _score.value = (score.value)?.inc()
         nextWord()
     }
+
+    fun onGameFinishComplete() {
+        _eventGameFinished.value = false
+    }
 }