Your First Kotlin Android App: An App From Scratch

Aug 15 2023 · Kotlin 1.8.20, Android 13, Android Studio Flamingo | 2022.2.1

Part 2: Manage Data in Jetpack Compose

15. Learn About State Hoisting

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Previous episode: 14. Understand State in Jetpack Compose Next episode: 16. Work with Strings

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In the previous episode, you triggered the update of the alertIsVisible state object that is defined in the GameScreen composable from an event inside the alert dialog.

import androidx.compose.runtime.Composable

@Composable
fun TargetSlider(modifier: Modifier = Modifier) {

}

@Composable
fun TargetSlider(modifier: Modifier = Modifier) {
  Row(
    verticalAlignment = Alignment.CenterVertically,
    modifier = modifier // Make sure you add this
  ) {
    Text(
      stringResource(id = R.string.min_value_text),
      textAlign = TextAlign.Center,
      modifier = Modifier.padding(start = 16.dp)
    )
    Slider(
      value = 0.5f,
      valueRange = 0.01f..1f,
      onValueChange = { },
      modifier = Modifier.weight(1f)
    )
    Text(
      stringResource(id = R.string.max_value_text),
      textAlign = TextAlign.Center,
      modifier = Modifier.padding(end = 16.dp)
    )
  }
}

TargetSlider()

fun TargetSlider(modifier: Modifier = Modifier, value: Float = 0.5f) {
  //...
}

Slider(
  value = value,
  //...
)

@Composable
fun TargetSlider(
  modifier: Modifier = Modifier
  value: Float = 0.5f,
  valueChanged: (Float) -> Unit, // New Code
) {
  //...
}

onValueChange = valueChanged,

var sliderValue by remember { mutableStateOf(0.5f) }

TargetSlider(
  value = sliderValue,
  valueChanged = { value ->
    sliderValue = value
  }
)