DisposableEffect — Jetpack Compose でのリソース解放

class SensorManager(private val context: Context) {
    fun startListening(callback: (Float) -> Unit) { /* register */ }
    fun stopListening() { /* cancel */ }
}

@Composable
fun SensorDisplay() {
    val sensorManager = remember { SensorManager(context) }
    var value by remember { mutableStateOf(0f) }
    
    DisposableEffect(Unit) {
        sensorManager.startListening { value = it }
        onDispose { sensorManager.stopListening() }
    }
    
    Text("センサー: $value")
}

// キーを使った正しい使い方
DisposableEffect(sensorType) {
    val sensor = sensorManager.getDefaultSensor(sensorType)
    sensorManager.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_NORMAL)
    
    onDispose {
        sensorManager.unregisterListener(listener)
    }
}

// 一つの DisposableEffect での複数のリソース
DisposableEffect(Unit) {
    context.registerReceiver(receiver, intentFilter)
    lifecycle.addObserver(observer)
    
    onDispose {
        context.unregisterReceiver(receiver)
        lifecycle.removeObserver(observer)
    }
}

@Composable
fun SensorReadingScreen(sensorType: Int) {
    val context = LocalContext.current
    val sensorManager = context.getSystemService(Context.SENSOR_SERVICE) as SensorManager
    var sensorValue by remember { mutableStateOf(0f) }
    
    DisposableEffect(sensorType) {
        val sensor = sensorManager.getDefaultSensor(sensorType)
        val listener = SensorEventListener { event, _ ->
            sensorValue = event.values[0]
        }
        sensorManager.registerListener(listener, sensor, SensorManager.SENSOR_DELAY_NORMAL)
        
        onDispose {
            sensorManager.unregisterListener(listener)
        }
    }
    
    Text("値: $sensorValue")
}

@Composable
fun NetworkStatusBanner() {
    val context = LocalContext.current
    var isConnected by remember { mutableStateOf(true) }
    
    DisposableEffect(Unit) {
        val receiver = BroadcastReceiver { _, _ ->
            val cm = context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
            isConnected = cm.getActiveNetwork() != null
        }
        IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION).let { filter ->
            context.registerReceiver(receiver, filter)
        }
        
        onDispose {
            context.unregisterReceiver(receiver)
        }
    }
    
    if (!isConnected) { ... }
}