A simple repeater that will repeat an action infinitely with a set interval until it is stopped. Uses Coroutines.

Repeater.kt

class Repeater(val interval: Long,
               val context: CoroutineContext = UI,
               val block: () -> Unit
) {
    private var updatingJob: Job? = null
    private val updatingJobLock = Any()

    fun start() = synchronized(updatingJobLock) {
        if (updatingJob != null && updatingJob!!.isActive) {
            return
        }
        updatingJob = launch(context) {
            while (isActive) {
                block()
                delay(interval)
            }
        }
    }

    fun stop() {
        updatingJob?.cancel()
        synchronized(updatingJobLock) {
            updatingJob = null
        }
    }
}