buttonGroup

Enrolls this button in group, so at most one of the buttons declared with it is selected. Requires an AbstractButton target (a radio button, a toggle button, a checkbox, or a button menu item).

val group = remember { ButtonGroup() }
sizes.forEachIndexed { index, size ->
    RadioButton(
        text = size,
        modifier = SwingModifier.buttonGroup(group),
        selected = index == choice,
        onSelectedChange = { choice = index },
    )
}

The caller owns the group, and holding it stable - remember { ButtonGroup() } - is what keeps the buttons declared with it one choice across recompositions. Membership follows the modifier: declaring a different group moves the button to it, and the button leaves the group when the modifier leaves the modifier chain or the component leaves the composition or parks, so a departed button stops taking part in the exclusion instead of lingering as a hidden member. One button belongs to one group: declaring two on the same modifier chain enrolls it in the last one.

A group owns which of its members is selected and only ever moves that selection: a member holds it until another one takes it, so declaring selected = false for every member leaves the one that has it selected, and a button declared selected takes the selection with it as it joins.

The user's choice reports through the button they activated, a choice of the member already holding the selection included: nothing moves, and that button reports the selection it holds. The member the group clears reports nothing and keeps its own declaration, which takes the selection back where the caller does not adopt the choice. A choice declared as an index, the empty choice included, is what RadioGroup takes.

Parameters

See also