Is it possible to `try catch` in Composable function? Code in :thread:

# compose

[Shakil Karim]

Is it possible to try catch in Composable function? Code in 🧵

[Shakil Karim]

@Composable
fun String.toAnnotatedString(): AnnotatedString? {
    return try {
        val pattern = Pattern.compile("\\*\\*(.*?)\\*\\*")
        val matcher = pattern.matcher(this)
        val sb = StringBuffer()
        val stringBuilder = AnnotatedString.Builder()
        while (matcher.find()) {
            sb.setLength(0)
            val group = matcher.group()
            val spanText = group.substring(2, group.length - 2)
            matcher.appendReplacement(sb, spanText)
            stringBuilder.append(sb.toString())
            val start = stringBuilder.length - spanText.length
            stringBuilder.addStyle(SpanStyle(color = MaterialTheme.colors.secondary),start = start,end = stringBuilder.length)
        }
        sb.setLength(0)
        matcher.appendTail(sb)
        stringBuilder.append(sb.toString())
        stringBuilder.toAnnotatedString()
    }catch (ex: Exception) {
        null
    }
}

[Dominaezzz]

I don't see why that has to be composable.

[Dominaezzz]

Ahh, MaterialTheme .

[Shakil Karim]

@Dominaezzz Because of MaterialTheme.colors.secondary

[Dominaezzz]

It's possible but I think it's bad practice. Best to move MaterialTheme.colors.secondary outside the try catch.

[Dominaezzz]

unrelated: Prefer StringBuilder over StringBuffer . StringBuffer is for multi-threaded use so it'll be slower.

[Shakil Karim]

Yeah Thanks, i didn't noticed that 👍

[Shakil Karim]

Actually, appendTail method expects StringBuffer

[Dominaezzz]

There's an overload that takes a StringBuilder

[Anton Popov]

https://kotlinlang.slack.com/archives/CJLTWPH7S/p1603748877143100?thread_ts=1603737209.131700&cid=CJLTWPH7S