try-with-resources: “use” extension function in Kotlin does not always work

Question

I had some trouble expressing the Java\'s try-with-resources construct in Kotlin. In my understanding, every expression that is an instance of AutoClosable shou

Answer 1

Kotlin targets Java 6 at the moment, so its standard library does not use the AutoCloseable interface. The use function only supports the Java 6 Closeable interface. See the issue tracker for reference.

You can create a copy of the use function in your project and modify it to replace Closeable with AutoCloseable:

public inline fun  T.use(block: (T) -> R): R {
    var closed = false
    try {
        return block(this)
    } catch (e: Exception) {
        closed = true
        try {
            close()
        } catch (closeException: Exception) {
            e.addSuppressed(closeException)
        }
        throw e
    } finally {
        if (!closed) {
            close()
        }
    }
}