CDRussell

private fun parse(url: String): ParseResult {
    val result = URL_PARSE_REGEX.find(url)
    if(result == null) {
        return ParseResult.Error("No match found")
    }

    val mimeType = result.groupValues[2]
    val data = result.groupValues[4]

    return ParseResult.ParsedData(data, mimeType)

CDRussell

sealed class ParseResult 

data class Error(val errorMessage: String) : ParseResult()
        
data class ParsedData(
    val data: String,
    val mimeType: String) : ParseResult()
    

CDRussell

class ResultWrapper(
    val data: ParsedData? = null,
    val errorMessage: String? = null
)

CDRussell

val result = parse(url)

if(result.errorMessage != null) {
    // error occurred - log error message etc... 
} else {
    // happy path - use the data. But result.data is nullable 🙄
    val mimeType = result.data!!.mimeType
}

CDRussell

private fun parse(url: String): ParsedData {
    val result = URL_PARSE_REGEX.find(url)
    
    if(result == null) {
        // what do we do here? Throw an exception? Return null?
    }

    val mimeType = result.groupValues[2]
    val data = result.groupValues[4]

CDRussell

taskDao.getAll().observe(this, Observer<List<Task>> {
    taskListAdapter.submitList(it)
})

CDRussell

class TaskDiffCallback : DiffUtil.ItemCallback<Task>() {
    override fun areItemsTheSame(oldItem: Task?, newItem: Task?): Boolean {
        return oldItem?.id == newItem?.id
    }

    override fun areContentsTheSame(oldItem: Task?, newItem: Task?): Boolean {
        return oldItem == newItem
    }
}

CDRussell

class TaskListAdapter(private val clickListener: (Task) -> Unit) :
    ListAdapter<Task, ViewHolder>(TaskDiffCallback()) {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val inflater = LayoutInflater.from(parent.context)
        return ViewHolder(inflater.inflate(R.layout.item_task_row, parent, false))
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        holder.bind(getItem(position), clickListener)

CDRussell

class TaskListAdapter : RecyclerView.Adapter<ViewHolder>() {

    private val tasks: MutableList<Task> = ArrayList()

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val inflater = LayoutInflater.from(parent.context)
        return ViewHolder(inflater.inflate(R.layout.item_task_row, parent, false))
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {

CDRussell

@Entity
data class Task(@PrimaryKey(autoGenerate = true) var id: Int = 0,
                var title: String = "",
                var completed: Boolean = false)