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Android Studio – pass method to Composable as parameter inside clickable lambda. The expression is unused

I have the following Composable

@Composable
fun ClickableBar(text: String, action: () -> Unit) {
    Row(
        modifier = Modifier
            .height(40.dp)
            .background(color = AppPrimaryGreen)
            .fillMaxWidth()
            .clickable { action },
        verticalAlignment = Alignment.CenterVertically
    ) {
        Text(text = text)

        Icon(
            painter = painterResource(R.drawable.icon_arrow_right),
            contentDescription = "",
        )
    }
}

I want to perform action method when that Row is tapped but action gets highlighted and it says The expression is unused.

What I’m doing wrong??

Tags:

2

Answers


  1. 0

    You need to call it like this:

    action()

    Since action is a lambda function passed to ClickableBar function, you need to include parentheses when invoking it, just like with any other function call.

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  2. 0

    There are actually two ways you can do this.

    dev.tejasb proposed the following to invoke the action function by adding parentheses:

    .clickable { action() }

    But you can also do this:

    .clickable(onClick = action)

    Both options provide a value for the onClick parameter. While the first option creates a new lambda and calls action in it, the second option directly passes action as the parameter. Note that onClick has the type () -> Unit, the same type as action so you can simply assign the parameter as in option 2.

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