#Radio button

A radio button lets a user select an option from a set of options. You use a radio button when only one item can be selected from a list. If users need to select more than one item, use a switch instead.

Figure 1. A pair of radio buttons with one option selected.

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#API surface

Use the RadioButton composable to list the available options. Wrap each RadioButton option and its label inside a Row component to group them together.

RadioButton includes the following key parameters:

• selected: Indicates whether the radio button is selected.
• onClick: A lambda function that your app executes when the user clicks the radio button. If this is null, the user can't interact directly with the radio button.
• enabled: Controls whether the radio button is enabled or disabled. Users can't interact with disabled radio buttons.
• interactionSource: Lets you observe the interaction state of the button, for example, whether it's pressed, hovered, or focused.

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#Create a basic radio button

The following code snippet renders a list of radio buttons within a Column:

kotlincopy@Composable
fun RadioButtonSingleSelection(modifier: Modifier = Modifier) {
    val radioOptions = listOf("Calls", "Missed", "Friends")
    val (selectedOption, onOptionSelected) = remember { mutableStateOf(radioOptions[0]) }

    // Note that Modifier.selectableGroup() is essential to ensure correct accessibility behavior
    Column(modifier.selectableGroup()) {
        radioOptions.forEach { text ->
            Row(
                Modifier
                    .fillMaxWidth()
                    .height(56.dp)
                    .selectable(
                        selected = (text == selectedOption),
                        onClick = { onOptionSelected(text) },
                        role = Role.RadioButton
                    )
                    .padding(horizontal = 16.dp),
                verticalAlignment = Alignment.CenterVertically
            ) {
                RadioButton(
                    selected = (text == selectedOption),
                    onClick = null // null recommended for accessibility with screen readers
                )
                Text(
                    text = text,
                    style = MaterialTheme.typography.bodyLarge,
                    modifier = Modifier.padding(start = 16.dp)
                )
            }
        }
    }
}

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#Key points about the code

• radioOptions represents the labels for the radio buttons.
• The remember composable function creates a state variable selectedOption and a function to update that state called onOptionSelected. This state holds the selected radio button option.
• mutableStateOf(radioOptions[0]) initializes the state to the first item in the list. "Calls" is the first item, so it's the radio button selected by default.
• Modifier.selectableGroup() ensures proper accessibility behavior for screen readers. It informs the system that the elements within this Column are part of a selectable group.
• Modifier.selectable() makes the entire Row act as a single selectable item.
• selected indicates whether the current Row is selected based on the selectedOption state.
• The onClick lambda function updates the selectedOption state to the clicked option when the Row is clicked.
• role = Role.RadioButton informs accessibility services that the Row functions as a radio button.
• RadioButton(...) creates the RadioButton composable.
• onClick = null on the RadioButton improves accessibility. This prevents the radio button from handling the click event directly and allows the Row's selectable modifier to manage the selection state and accessibility behavior.

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#Result

A list of three radio buttons labeled Calls, Missed, and Friends.

Figure 2. Three radio buttons with the "Friends" option selected.