Tugas 7 - View Model & State in Compose

Nama    : Syaiful Bahri Dirgantara

Kelas    : PPB F

Pendahuluan

Pada pertemuan kali ini dijelaskan mengenai penggunaan dari ViewModel dan State dalam Kotlin menggunakan compose. Kali ini diimplementasikan ke dalam sebuah game scramble world. Fungsi penggunaan ViewModel dan State dalam compose ini adalah supaya ketika terjadi suatu perubahan seperti saat berpindah dari portrait ke landscape aplikasi tidak mulai dari awal lagi.

Tampilan implementasi

Tampilan aplikasi sebelum mendapatkan kata yang benar skor masih 0

Tampilan aplikasi setelah mendapatkan kata yang benar maka skor bertambah menjadi 20

Tampilan saat aplikasi dipindah ke landscape skor tetap

Source Code : 

1. MainActivity.kt

package com.example.unscramble

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.activity.enableEdgeToEdge
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material3.Surface
import androidx.compose.ui.Modifier
import com.example.unscramble.ui.GameScreen
import com.example.unscramble.ui.theme.UnscrambleTheme

class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        enableEdgeToEdge()
        super.onCreate(savedInstanceState)
        setContent {
            UnscrambleTheme {
                Surface(
                    modifier = Modifier.fillMaxSize(),
                ) {
                    GameScreen()
                }
            }
        }
    }
}

2. GameScreen.kt

package com.example.unscramble.ui

import android.app.Activity
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.safeDrawingPadding
import androidx.compose.foundation.layout.statusBarsPadding
import androidx.compose.foundation.layout.wrapContentHeight
import androidx.compose.foundation.rememberScrollState
import androidx.compose.foundation.text.KeyboardActions
import androidx.compose.foundation.text.KeyboardOptions
import androidx.compose.foundation.verticalScroll
import androidx.compose.material3.AlertDialog
import androidx.compose.material3.Button
import androidx.compose.material3.Card
import androidx.compose.material3.CardDefaults
import androidx.compose.material3.MaterialTheme.colorScheme
import androidx.compose.material3.MaterialTheme.shapes
import androidx.compose.material3.MaterialTheme.typography
import androidx.compose.material3.OutlinedButton
import androidx.compose.material3.OutlinedTextField
import androidx.compose.material3.Text
import androidx.compose.material3.TextButton
import androidx.compose.material3.TextFieldDefaults
import androidx.compose.runtime.Composable
import androidx.compose.runtime.collectAsState
import androidx.compose.runtime.getValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.clip
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.res.dimensionResource
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.text.input.ImeAction
import androidx.compose.ui.text.style.TextAlign
import androidx.compose.ui.tooling.preview.Preview
import androidx.compose.ui.unit.dp
import androidx.compose.ui.unit.sp
import androidx.lifecycle.viewmodel.compose.viewModel
import com.example.unscramble.R
import com.example.unscramble.ui.theme.UnscrambleTheme

@Composable
fun GameScreen(gameViewModel: GameViewModel = viewModel()) {
    val gameUiState by gameViewModel.uiState.collectAsState()
    val mediumPadding = dimensionResource(R.dimen.padding_medium)

    Column(
        modifier = Modifier
            .statusBarsPadding()
            .verticalScroll(rememberScrollState())
            .safeDrawingPadding()
            .padding(mediumPadding),
        verticalArrangement = Arrangement.Center,
        horizontalAlignment = Alignment.CenterHorizontally
    ) {

        Text(
            text = stringResource(R.string.app_name),
            style = typography.titleLarge,
        )
        GameLayout(
            onUserGuessChanged = { gameViewModel.updateUserGuess(it) },
            wordCount = gameUiState.currentWordCount,
            userGuess = gameViewModel.userGuess,
            onKeyboardDone = { gameViewModel.checkUserGuess() },
            currentScrambledWord = gameUiState.currentScrambledWord,
            isGuessWrong = gameUiState.isGuessedWordWrong,
            modifier = Modifier
                .fillMaxWidth()
                .wrapContentHeight()
                .padding(mediumPadding)
        )
        Column(
            modifier = Modifier
                .fillMaxWidth()
                .padding(mediumPadding),
            verticalArrangement = Arrangement.spacedBy(mediumPadding),
            horizontalAlignment = Alignment.CenterHorizontally
        ) {

            Button(
                modifier = Modifier.fillMaxWidth(),
                onClick = { gameViewModel.checkUserGuess() }
            ) {
                Text(
                    text = stringResource(R.string.submit),
                    fontSize = 16.sp
                )
            }

            OutlinedButton(
                onClick = { gameViewModel.skipWord() },
                modifier = Modifier.fillMaxWidth()
            ) {
                Text(
                    text = stringResource(R.string.skip),
                    fontSize = 16.sp
                )
            }
        }

        GameStatus(score = gameUiState.score, modifier = Modifier.padding(20.dp))

        if (gameUiState.isGameOver) {
            FinalScoreDialog(
                score = gameUiState.score,
                onPlayAgain = { gameViewModel.resetGame() }
            )
        }
    }
}

@Composable
fun GameStatus(score: Int, modifier: Modifier = Modifier) {
    Card(
        modifier = modifier
    ) {
        Text(
            text = stringResource(R.string.score, score),
            style = typography.headlineMedium,
            modifier = Modifier.padding(8.dp)
        )

    }
}

@Composable
fun GameLayout(
    currentScrambledWord: String,
    wordCount: Int,
    isGuessWrong: Boolean,
    userGuess: String,
    onUserGuessChanged: (String) -> Unit,
    onKeyboardDone: () -> Unit,
    modifier: Modifier = Modifier
) {
    val mediumPadding = dimensionResource(R.dimen.padding_medium)

    Card(
        modifier = modifier,
        elevation = CardDefaults.cardElevation(defaultElevation = 5.dp)
    ) {
        Column(
            verticalArrangement = Arrangement.spacedBy(mediumPadding),
            horizontalAlignment = Alignment.CenterHorizontally,
            modifier = Modifier.padding(mediumPadding)
        ) {
            Text(
                modifier = Modifier
                    .clip(shapes.medium)
                    .background(colorScheme.surfaceTint)
                    .padding(horizontal = 10.dp, vertical = 4.dp)
                    .align(alignment = Alignment.End),
                text = stringResource(R.string.word_count, wordCount),
                style = typography.titleMedium,
                color = colorScheme.onPrimary
            )
            Text(
                text = currentScrambledWord,
                style = typography.displayMedium
            )
            Text(
                text = stringResource(R.string.instructions),
                textAlign = TextAlign.Center,
                style = typography.titleMedium
            )
            OutlinedTextField(
                value = userGuess,
                singleLine = true,
                shape = shapes.large,
                modifier = Modifier.fillMaxWidth(),
                colors = TextFieldDefaults.colors(
                    focusedContainerColor = colorScheme.surface,
                    unfocusedContainerColor = colorScheme.surface,
                    disabledContainerColor = colorScheme.surface,
                ),
                onValueChange = onUserGuessChanged,
                label = {
                    if (isGuessWrong) {
                        Text(stringResource(R.string.wrong_guess))
                    } else {
                        Text(stringResource(R.string.enter_your_word))
                    }
                },
                isError = isGuessWrong,
                keyboardOptions = KeyboardOptions.Default.copy(
                    imeAction = ImeAction.Done
                ),
                keyboardActions = KeyboardActions(
                    onDone = { onKeyboardDone() }
                )
            )
        }
    }
}

/*
 * Creates and shows an AlertDialog with final score.
 */
@Composable
private fun FinalScoreDialog(
    score: Int,
    onPlayAgain: () -> Unit,
    modifier: Modifier = Modifier
) {
    val activity = (LocalContext.current as Activity)

    AlertDialog(
        onDismissRequest = {
            // Dismiss the dialog when the user clicks outside the dialog or on the back
            // button. If you want to disable that functionality, simply use an empty
            // onCloseRequest.
        },
        title = { Text(text = stringResource(R.string.congratulations)) },
        text = { Text(text = stringResource(R.string.you_scored, score)) },
        modifier = modifier,
        dismissButton = {
            TextButton(
                onClick = {
                    activity.finish()
                }
            ) {
                Text(text = stringResource(R.string.exit))
            }
        },
        confirmButton = {
            TextButton(onClick = onPlayAgain) {
                Text(text = stringResource(R.string.play_again))
            }
        }
    )
}

@Preview(showBackground = true)
@Composable
fun GameScreenPreview() {
    UnscrambleTheme {
        GameScreen()
    }
}

3. GameUiState.kt

package com.example.unscramble.ui

/**
 * Data class that represents the game UI state
 */
data class GameUiState(
    val currentScrambledWord: String = "",
    val currentWordCount: Int = 1,
    val score: Int = 0,
    val isGuessedWordWrong: Boolean = false,
    val isGameOver: Boolean = false
)

4. GameViewModel.kt

package com.example.unscramble.ui

import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.setValue
import androidx.lifecycle.ViewModel
import com.example.unscramble.data.MAX_NO_OF_WORDS
import com.example.unscramble.data.SCORE_INCREASE
import com.example.unscramble.data.allWords
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow
import kotlinx.coroutines.flow.update

/**
 * ViewModel containing the app data and methods to process the data
 */
class GameViewModel : ViewModel() {

    // Game UI state
    private val _uiState = MutableStateFlow(GameUiState())
    val uiState: StateFlow<GameUiState> = _uiState.asStateFlow()

    var userGuess by mutableStateOf("")
        private set

    // Set of words used in the game
    private var usedWords: MutableSet<String> = mutableSetOf()
    private lateinit var currentWord: String

    init {
        resetGame()
    }

    /*
     * Re-initializes the game data to restart the game.
     */
    fun resetGame() {
        usedWords.clear()
        _uiState.value = GameUiState(currentScrambledWord = pickRandomWordAndShuffle())
    }

    /*
     * Update the user's guess
     */
    fun updateUserGuess(guessedWord: String){
        userGuess = guessedWord
    }

    /*
     * Checks if the user's guess is correct.
     * Increases the score accordingly.
     */
    fun checkUserGuess() {
        if (userGuess.equals(currentWord, ignoreCase = true)) {
            // User's guess is correct, increase the score
            // and call updateGameState() to prepare the game for next round
            val updatedScore = _uiState.value.score.plus(SCORE_INCREASE)
            updateGameState(updatedScore)
        } else {
            // User's guess is wrong, show an error
            _uiState.update { currentState ->
                currentState.copy(isGuessedWordWrong = true)
            }
        }
        // Reset user guess
        updateUserGuess("")
    }

    /*
     * Skip to next word
     */
    fun skipWord() {
        updateGameState(_uiState.value.score)
        // Reset user guess
        updateUserGuess("")
    }

    /*
     * Picks a new currentWord and currentScrambledWord and updates UiState according to
     * current game state.
     */
    private fun updateGameState(updatedScore: Int) {
        if (usedWords.size == MAX_NO_OF_WORDS){
            //Last round in the game, update isGameOver to true, don't pick a new word
            _uiState.update { currentState ->
                currentState.copy(
                    isGuessedWordWrong = false,
                    score = updatedScore,
                    isGameOver = true
                )
            }
        } else{
            // Normal round in the game
            _uiState.update { currentState ->
                currentState.copy(
                    isGuessedWordWrong = false,
                    currentScrambledWord = pickRandomWordAndShuffle(),
                    currentWordCount = currentState.currentWordCount.inc(),
                    score = updatedScore
                )
            }
        }
    }

    private fun shuffleCurrentWord(word: String): String {
        val tempWord = word.toCharArray()
        // Scramble the word
        tempWord.shuffle()
        while (String(tempWord) == word) {
            tempWord.shuffle()
        }
        return String(tempWord)
    }

    private fun pickRandomWordAndShuffle(): String {
        // Continue picking up a new random word until you get one that hasn't been used before
        currentWord = allWords.random()
        return if (usedWords.contains(currentWord)) {
            pickRandomWordAndShuffle()
        } else {
            usedWords.add(currentWord)
            shuffleCurrentWord(currentWord)
        }
    }
}

5. WordsData.kt

package com.example.unscramble.data

const val MAX_NO_OF_WORDS = 10
const val SCORE_INCREASE = 20

// Set with all the words for the Game
val allWords: Set<String> =
    setOf(
        "animal",
        "auto",
        "anecdote",
        "alphabet",
        "all",
        "awesome",
        "arise",
        "balloon",
        "basket",
        "bench",
        "best",
        "birthday",
        "book",
        "briefcase",
        "camera",
        "camping",
        "candle",
        "cat",
        "cauliflower",
        "chat",
        "children",
        "class",
        "classic",
        "classroom",
        "coffee",
        "colorful",
        "cookie",
        "creative",
        "cruise",
        "dance",
        "daytime",
        "dinosaur",
        "doorknob",
        "dine",
        "dream",
        "dusk",
        "eating",
        "elephant",
        "emerald",
        "eerie",
        "electric",
        "finish",
        "flowers",
        "follow",
        "fox",
        "frame",
        "free",
        "frequent",
        "funnel",
        "green",
        "guitar",
        "grocery",
        "glass",
        "great",
        "giggle",
        "haircut",
        "half",
        "homemade",
        "happen",
        "honey",
        "hurry",
        "hundred",
        "ice",
        "igloo",
        "invest",
        "invite",
        "icon",
        "introduce",
        "joke",
        "jovial",
        "journal",
        "jump",
        "join",
        "kangaroo",
        "keyboard",
        "kitchen",
        "koala",
        "kind",
        "kaleidoscope",
        "landscape",
        "late",
        "laugh",
        "learning",
        "lemon",
        "letter",
        "lily",
        "magazine",
        "marine",
        "marshmallow",
        "maze",
        "meditate",
        "melody",
        "minute",
        "monument",
        "moon",
        "motorcycle",
        "mountain",
        "music",
        "north",
        "nose",
        "night",
        "name",
        "never",
        "negotiate",
        "number",
        "opposite",
        "octopus",
        "oak",
        "order",
        "open",
        "polar",
        "pack",
        "painting",
        "person",
        "picnic",
        "pillow",
        "pizza",
        "podcast",
        "presentation",
        "puppy",
        "puzzle",
        "recipe",
        "release",
        "restaurant",
        "revolve",
        "rewind",
        "room",
        "run",
        "secret",
        "seed",
        "ship",
        "shirt",
        "should",
        "small",
        "spaceship",
        "stargazing",
        "skill",
        "street",
        "style",
        "sunrise",
        "taxi",
        "tidy",
        "timer",
        "together",
        "tooth",
        "tourist",
        "travel",
        "truck",
        "under",
        "useful",
        "unicorn",
        "unique",
        "uplift",
        "uniform",
        "vase",
        "violin",
        "visitor",
        "vision",
        "volume",
        "view",
        "walrus",
        "wander",
        "world",
        "winter",
        "well",
        "whirlwind",
        "x-ray",
        "xylophone",
        "yoga",
        "yogurt",
        "yoyo",
        "you",
        "year",
        "yummy",
        "zebra",
        "zigzag",
        "zoology",
        "zone",
        "zeal"
    )