Android Kotlin Fundamentalsで学ぶ　その５

dependencies{
    ...
    // 追記
    implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
}

...
import androidx.lifecycle.ViewModel

class GameViewModel: ViewModel(){  // ViewModelをインプリメントする
    init{
        /* ViewModelの初期化時に呼び出される。チェック用 */
        Log.i("GameViewModel", "1. GameViewModel created!")
    }
    
    /* フラグメントが破棄された時に呼び出される。チェック用 */
    override fun onCleared(){
        super.onCleared()
	Log.i("GameViewModel", "2. GameViewModel destroyed!")
    }

class GameFragment: Fragment(){
    ...
    // 追記
    private lateinit var viewModel: GameViewModel
    
    override fun onCreateView(...){
    ...
    

    onCreateView(...){
        ...
	/* フラグメント作成時に呼び出される。チェック用 */
        Log.i("GameFragment", "3. Called ViewModelProvider.get")
        viewModel = ViewModelProvider(this).get(GameViewModel::class.java)
	...
    }

class GameViewModel: ViewModel(){
    /* 変数の定義 */
    var word = ""
    var score = 0
    private lateinit var wordList: MutableList<String>
    
    private fun resetList(){
        wordList = mutableListOf(
	    "queen",
	    ...
	)
	wordList.shuffle()
    }
    
    init{
       resetList()
       nextWord()
    }
     /* 処理の定義 */
    private fun nextWord(){ ... }
    fun onSkip() { ... }
    fun onCorrect() { ... }
    
    ...
}

class GameFragment: Fragment(){
    /* 変数定義以外そのまま */
    private lateinit var binding: GameFragmentBinding
    private lateinit var viewModel: GameViewModel
    
    override fun onCreateView(...){...}
    
    /* 処理はViewModelから呼び出す */
    private fun onSkip() {
        viewModel.onSkip()
	...
    }

    private fun onCorrect() {
        viewModel.onCorrect()
	...
    }
    
    /* 変数'word', 'score' はViewModelからとってくる */
    private fun updateWordText() {
        binding.wordText.text = viewModel.word
    }

    private fun updateScoreText() {
        binding.scoreText.text = viewModel.score.toString()
    }
}

private fun gameFinished() {
   // GameFragment→ScoreFragment
   val action = GameFragmentDirections.actionGameToScore()
   // スコアを追加する
   action.score = viewModel.score
   // Navigationで遷移させる
   NavHostFragment.findNavController(this).navigate(action)
}

├── ScoreFragment.kt
├── ScoreViewModel.kt
└── ScoreViewModelFactory.kt

class ScoreViewModel(finalScore: Int) : ViewModel() {
   // The final score
   var score = finalScore
}

/* ViewModelProvider.Factoryを継承 */
class ScoreViewModelFactory(private val finalScore: Int) : ViewModelProvider.Factory {
    override fun <T : ViewModel?> create(modelClass: Class<T>): T {
        if(modelClass.isAssignableFrom(ScoreViewModel::class.java)){
            return ScoreViewModel(finalScore) as T
        }
        throw IllegalArgumentException("Unknown ViewModel class")
    }
}

class ScoreFragment : Fragment() {

    private lateinit var viewModel: ScoreViewModel
    private lateinit var viewModelFactory: ScoreViewModelFactory

    override fun onCreateView(
            inflater: LayoutInflater,
            container: ViewGroup?,
            savedInstanceState: Bundle?
    ): View? {

        // Inflate view and obtain an instance of the binding class.
        val binding: ScoreFragmentBinding = DataBindingUtil.inflate( ... )
	/* ViewModelFactoryを初期化し、バンドルからscoreを取得し、引数にする */
        viewModelFactory = ScoreViewModelFactory(ScoreFragmentArgs.fromBundle(requireArguments()).score)
	/* ViewModelの初期化をし、getメソッドでViewModelFactoryを渡すことでViewModelオブジェクトが作成される */
        viewModel = ViewModelProvider(this, viewModelFactory)
                .get(ScoreViewModel::class.java)
        binding.scoreText.text = viewModel.score.toString()

        return binding.root
    }
}

val word = ""
val score = 0

val word = MutableLiveData<String>()
val score = MutableLiveData<Int>()

init{
    word.value = ""
    score.value = 0
    ...
}

...
override fun onCreateView(...){
    ...
    viewModel.score.observe(viewLifecycleOwner, Observer { newScore ->
        binding.scoreText.text = newScore.toString()
    })
    viewModel.word.observe(viewLifecycleOwner, Observer { newWord ->
        binding.wordText.text = newWord
    })
    ...

private val _score = MutableLiveData<Int>()
val score: LiveData<Int>
    get() = _score
init{
    ...
    _score.value = 0
    ...
}

private val _eventGameFinish = MutableLiveData<Boolean>()
val eventGameFinish: LiveData<Boolean>
   get() = _eventGameFinish
...
// END GAMEボタンを押したら
fun onGameFinish() {
   _eventGameFinish.value = true
}
private fun nextWord() {
   if (wordList.isEmpty()) {  // 全問終えたら
       onGameFinish()
   } else {
       _word.value = wordList.removeAt(0)
   }
}

override fun onCreateView(...){
    viewModel.eventGameFinish.observe(viewLifecycleOwner, Observer<Boolean> { hasFinished ->
        if (hasFinished) gameFinished()
    })
   ...
}

    fun onGameFinishComplete(){
        _eventGameFinish.value = false
    }

    private fun gameFinished(){
         ...
	 viewModel.onGameFinishedComplete()
    }

<layout ...>
    <data>
        <variable
	     name="gameViewModel"
	     type="com.example.android.guesstheword.screens.game.GameViewModel" />
    </data>
    ...

override fun onCreateView(...){
    ...
    binging.gameViewModel = viewModel
    ...
}

<Button
   android:id="@+id/skip_button"
   ...
   android:onClick="@{() -> gameViewModel.onSkip()}"  // ラムダ式
   ... />
<Button
   android:id="@+id/correct_button"
   ...
   android:onClick="@{() -> gameViewModel.onCorrect()}"
   ... />
<Button
   android:id="@+id/end_game_button"
   ...
   android:onClick="@{() -> gameViewModel.onGameFinish()}"
   ... />

binding.correctButton.setOnClickListener { onCorrect() }
binding.skipButton.setOnClickListener { onSkip() }
binding.endGameButton.setOnClickListener { onEndGame() }

/** Methods for buttons presses **/
private fun onSkip() {
   viewModel.onSkip()
}
private fun onCorrect() {
   viewModel.onCorrect()
}
private fun onEndGame() {
   gameFinished()
}

    // word
    <TextView
	android:id="@+id/word_text"
	...
	android:text="@{gameViewModel.word}"
   ... />
   // score
   <TextView
	android:id="@+id/score_text"
	...
	android:text="@{String.valueOf(scoreViewModel.score)}"
   ... />

    binding.scoreViewModel = ...
    binding.lifecycleOwner = viewLifecycleOwner

    viewModel.score.observe(viewLifecycleOwner, Observer { newScore ->
        binding.scoreText.text = newScore.toString()
    })
    viewModel.score.observe(viewLifecycleOwner, Observer { newScore ->
        binding.scoreText.text = newScore.toString()
    })

<string name="quote_format">\"%s\"</string>
<string name="score_format">Current Score: %d</string>

    // word
    <TextView
	android:id="@+id/word_text"
	...
	android:text="@{@string/quote_format(gameViewModel.word)}"
   ... />
   // score
   <TextView
	android:id="@+id/score_text"
	...
	android:text="@{@string/score_format(scoreViewModel.score)}"
   ... />

    companion object {
        private const val DONE = 0L
        private const val ONE_SECOND = 1000L
        private const val COUNTDOWN_TIME = 60000L
    }

    // タイマーの設定
    private val timer: CountDownTimer
    // 初期化
    init {
	...
        // タイマーの初期化
        // 合計時間: COUNTDOWN_TIME, 間隔: ONE_SECOND を渡す
        timer = object : CountDownTimer(COUNTDOWN_TIME, ONE_SECOND) {
            override fun onTick(millisUntilFinished: Long) {
                // ティック(今回は1秒)ごとに呼び出される, _currentTimeを更新
                _currentTime.value = millisUntilFinished / ONE_SECOND
                Log.d("GameViewModel", "_currentTime: " + _currentTime.value.toString())
            }

            // タイマーが終了したら呼び出される, ゲーム終了
            override fun onFinish() {
                _currentTime.value = DONE
                onGameFinish()
            }
        }
        timer.start()
    }

    // Right before the ViewModel is destroyed, callback this method
    override fun onCleared() {
        super.onCleared()
        // メモリリーク回避のためにタイマーを削除
        timer.cancel()
        Log.i("GameViewModel", "2. GameViewModel destroyed!")
    }

    // currentTime定義後
    val currentTimeString = Transformations.map(currentTime){ time ->
        DateUtils.formatElapsedTime(time)
    }

<TextView
   android:id="@+id/timer_text"
   ...
   android:text="@{gameViewModel.currentTimeString}"
   ... />

   <data>

       <variable
           name="gameViewModel"
           type="com.example.android.guesstheword.screens.game.GameViewModel" />
   </data>