concurrency_interview_3.kt

val hashMap = ConcurrentHashMap<String, Bitmap?>()

job = scope.launch {
    val bitmap = if (hashMap.containsKey(url)) {
        hashMap[url]
    } else {
        val bitmap = loadBitmap(url)
        if (!hashMap.containsKey(url)) {
            hashMap[url] = bitmap
            bitmap
        } else {
            hashMap[url]
        }
    }

    withContext(Dispatchers.Main) {
        setImageBitmap(bitmap)
    }
}