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코드랩 LiveData transformations(kotlin)

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코드랩 LiveData transformations

ezgif com-gif-maker (4)

###정리

companion object 란 !

  • java의 static과 유사함 객체생성 없이 바로 접근 가능하도록 !
  • 클래스당 하나만 가질 수 있다.

CountDownTimer

CountDownTimer(millisInFuture, countDownInterval){
override fun onTick(p0: Long) {  
   //p0: 호출된 시점부터 종료될때까지 남은 시간
}  
  
override fun onFinish() {  
	//카운트 종료 
}
  • millisInFuture
    얼마동안 타이머를 실행 시킬건지 ms(1/1000초) 단위
  • countDownInterval
    줄어드는 시간 간격 설정

*timer.cancel() 꼭 해주기

Transformation.map()
설정된 각 값을 적용시켜서 매핑된 값을 반환함
formatElapsedTime
MM:SS 또는 H:MM:SS형식으로 경과 시간 형식화함 별도의 스레드를 사용하지 않고 UI 스레드에서 실행됨

코드

< game_fragment.xml >

<?xml version="1.0" encoding="utf-8"?><!--  
 ~ Copyright (C) 2019 Google Inc. ~ ~ Licensed under the Apache License, Version 2.0 (the "License"); ~ you may not use this file except in compliance with the License. ~ You may obtain a copy of the License at ~ ~     http://www.apache.org/licenses/LICENSE-2.0 ~ ~ Unless required by applicable law or agreed to in writing, software ~ distributed under the License is distributed on an "AS IS" BASIS, ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. ~ See the License for the specific language governing permissions and ~ limitations under the License. -->  
<layout xmlns:android="http://schemas.android.com/apk/res/android"  
  xmlns:app="http://schemas.android.com/apk/res-auto"  
  xmlns:tools="http://schemas.android.com/tools">  
  
 <data> <variable  name="gameViewModel"  
  type="com.example.android.guesstheword.screens.game.GameViewModel" />  
 </data>  
 <androidx.constraintlayout.widget.ConstraintLayout  android:id="@+id/game_layout"  
  android:layout_width="match_parent"  
  android:layout_height="match_parent"  
  tools:context=".screens.game.GameFragment">  
  
 <TextView  android:id="@+id/word_is_text"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginBottom="16dp"  
  android:fontFamily="sans-serif"  
  android:text="@string/word_is"  
  android:textColor="@color/black_text_color"  
  android:textSize="14sp"  
  android:textStyle="normal"  
  app:layout_constraintBottom_toTopOf="@+id/word_text"  
  app:layout_constraintEnd_toEndOf="parent"  
  app:layout_constraintHorizontal_bias="0.5"  
  app:layout_constraintStart_toStartOf="parent"  
  app:layout_constraintTop_toTopOf="parent"  
  app:layout_constraintVertical_chainStyle="packed" />  
  
 <TextView  android:id="@+id/word_text"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:animateLayoutChanges="true"  
  android:text = "@{@string/quote_format(gameViewModel.word)}"  
  android:fontFamily="sans-serif"  
  android:textAppearance="@style/TextAppearance.AppCompat.Headline"  
  android:textColor="@color/black_text_color"  
  android:textSize="34sp"  
  android:textStyle="normal"  
  app:layout_constraintBottom_toTopOf="@+id/score_text"  
  app:layout_constraintEnd_toEndOf="parent"  
  app:layout_constraintHorizontal_bias="0.5"  
  app:layout_constraintStart_toStartOf="parent"  
  app:layout_constraintTop_toBottomOf="@+id/word_is_text"  
  app:layout_constraintVertical_chainStyle="packed"  
  tools:text="&quot;Tuna&quot;" />  
  
 <TextView  android:id="@+id/tv_hint"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginTop="20dp"  
  android:textSize ="18sp"  
  android:text="@{gameViewModel.wordHint}"  
  app:layout_constraintEnd_toEndOf="parent"  
  app:layout_constraintHorizontal_bias="0.498"  
  app:layout_constraintStart_toStartOf="parent"  
  app:layout_constraintTop_toBottomOf="@+id/word_text" />  
  
 <TextView  android:id="@+id/timer_text"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginStart="8dp"  
  android:layout_marginEnd="8dp"  
  android:layout_marginBottom="8dp"  
  android:fontFamily="sans-serif"  
  android:text="@{gameViewModel.currentTimeString}"  
  android:textColor="@color/grey_text_color"  
  android:textSize="14sp"  
  android:textStyle="normal"  
  app:layout_constraintBottom_toTopOf="@+id/score_text"  
  app:layout_constraintEnd_toEndOf="parent"  
  app:layout_constraintStart_toStartOf="parent"  
  tools:text="0:00" />  
  
 <TextView  android:id="@+id/score_text"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginStart="8dp"  
  android:layout_marginEnd="8dp"  
  android:fontFamily="sans-serif"  
  android:textColor="@color/grey_text_color"  
  android:textSize="14sp"  
  android:textStyle="normal"  
  app:layout_constraintBottom_toTopOf="@+id/guideline"  
  app:layout_constraintEnd_toEndOf="parent"  
  app:layout_constraintStart_toStartOf="parent"  
  android:text="@{@string/score_format(gameViewModel.score)}"  
  />  
  
 <Button  android:id="@+id/skip_button"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginStart="16dp"  
  android:text="@string/skip"  
  android:onClick="@{()->gameViewModel.onSkip()}"  
  android:theme="@style/SkipButton"  
  app:layout_constraintBottom_toBottomOf="parent"  
  app:layout_constraintHorizontal_chainStyle="spread_inside"  
  app:layout_constraintStart_toStartOf="parent"  
  app:layout_constraintTop_toTopOf="@+id/guideline" />  
  
 <androidx.constraintlayout.widget.Guideline  android:id="@+id/guideline"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:orientation="horizontal"  
  app:layout_constraintGuide_end="96dp" />  
  
 <Button  android:id="@+id/correct_button"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginStart="8dp"  
  android:layout_marginEnd="8dp"  
  android:text="@string/got_it"  
  android:onClick="@{()->gameViewModel.onCorrect()}"  
  android:theme="@style/GoButton"  
  app:layout_constraintBottom_toBottomOf="parent"  
  app:layout_constraintEnd_toStartOf="@+id/end_game_button"  
  app:layout_constraintStart_toEndOf="@+id/skip_button"  
  app:layout_constraintTop_toTopOf="@+id/guideline" />  
  
 <Button  android:id="@+id/end_game_button"  
  android:layout_width="wrap_content"  
  android:layout_height="wrap_content"  
  android:layout_marginEnd="16dp"  
  android:text="@string/end_game"  
  android:onClick="@{()->gameViewModel.onEndGame()}"  
  android:theme="@style/SkipButton"  
  app:layout_constraintBottom_toBottomOf="parent"  
  app:layout_constraintEnd_toEndOf="parent"  
  app:layout_constraintTop_toTopOf="@+id/guideline" />  
  
 </androidx.constraintlayout.widget.ConstraintLayout></layout>

< GameViewModel.kt >

package com.example.android.guesstheword.screens.game  
  
import android.os.CountDownTimer  
import android.text.format.DateUtils  
import android.util.Log  
import androidx.lifecycle.LiveData  
import androidx.lifecycle.MutableLiveData  
import androidx.lifecycle.Transformations  
import androidx.lifecycle.ViewModel  
  
class GameViewModel : ViewModel() {  
  
  //LiveData 캡슐화  
  // The current word  
  private val _word = MutableLiveData<String>()  
  val word : LiveData<String>  
  get() = _word  
  
    // The current score  
  private val _score = MutableLiveData<Int>()  
  val score : LiveData<Int>  
  get() = _score  
  
    private val _eventGameFinish = MutableLiveData<Boolean>()  
  val eventGameFinish : LiveData<Boolean>  
  get() = _eventGameFinish  
  
    // The list of words - the front of the list is the next word to guess  
  private lateinit var wordList: MutableList<String>  
  
  companion object {  
  private const val DONE = 0L  
  private const val ONE_SECOND = 1000L //1초  
  private const val COUNTDOWN_TIME = 5000L //5초  
  }  
  
  private val _currentTime = MutableLiveData<Long>()  
  val currentTime : LiveData<Long>  
  get() = _currentTime  
  
    private val timer: CountDownTimer  
  
  val currentTimeString = Transformations.map(currentTime){ time ->  
  DateUtils.formatElapsedTime(time)  
  
  }  
  
  val wordHint = Transformations.map(word){ word ->  
  val randomPosition = (1..word.length).random()  
  "Current word has " + word.length +" letters" +  
  "\n The letter at position" + randomPosition + " is "+  
  word.get(randomPosition)  
  }  
  
  //GameFragment 들어가면 실행  
  init {  
  _word.value = ""  
  _score.value = 0  
  resetList()  
  nextWord()  
  
  timer = object : CountDownTimer(COUNTDOWN_TIME, ONE_SECOND){  
  override fun onTick(p0: Long) {  
  _currentTime.value = p0/ ONE_SECOND  
            }  
  
  override fun onFinish() {  
  _currentTime.value = DONE  
                onEndGame()  
 } }  timer.start()  
  
 }  
  /**  
 * Resets the list of words and randomizes the order */  private fun resetList() {  
  wordList = mutableListOf(  
  "queen",  
                "hospital",  
                "basketball",  
                "cat",  
                "change",  
                "snail",  
                "soup",  
                "calendar",  
                "sad",  
                "desk",  
                "guitar",  
                "home",  
                "railway",  
                "zebra",  
                "jelly",  
                "car",  
                "crow",  
                "trade",  
                "bag",  
                "roll",  
                "bubble"  
  )  
  wordList.shuffle()  
 }  
  /** Methods for buttons presses **/  
  
  
 /** * Moves to the next word in the list */  private fun nextWord() {  
  if (!wordList.isEmpty()) {  
  //Select and remove a word from the list  
  _word.value = wordList.removeAt(0)  
 }else{  
  resetList()  
 } }  
  /** Methods for updating the UI **/  
  
  fun onSkip() {  
  _score.value = (score.value)?.minus(1)  
  nextWord()  
 }  
  fun onCorrect() {  
  _score.value = (score.value)?.plus(1)  
  nextWord()  
 }  
  //GameFragment 벗어났을때 실행 (다른화면으로 넘어감)  
  override fun onCleared() {  
  super.onCleared()  
  timer.cancel()  
  
 }  
  fun onEndGame(){  
  _eventGameFinish.value = true  
  }  
  
  fun onEndGameFinished(){  
  _eventGameFinish.value =false  
  }  
  
}

참고 https://developer.android.com/codelabs/kotlin-android-training-live-data-transformations#0

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