How to format Firestore server timestamp in kotlin?-CodePudding

After I retrieve the date of data field from Firestore's Timestamp. I want to format my Timestamp date to "dd MMM yyyy, HH:mm" in my recyclerview. I tried to use DateTimeFormatter but it doesn't works.

    override fun onBindViewHolder(holder: OrderListViewHolder, position: Int) {
        val item = orderList[position]

        orderViewModel.setOrderProduct(item.foodItem)
        orderViewModel.setStatus(item.status)


        val foodItem = item.foodItem?.map { it.itemName }

        val date = Date(item.date!!.toDate().time)
        val newDate = date.toString().substring(0, 16)   date.toString().substring(29, 34)
        val formatter = DateTimeFormatter.ofPattern("dd MMM yyyy, HH:mm")
        val formattedDate = newDate.format(formatter)

        Log.d("dates", "${formattedDate}")

        holder.orderDate.text = formattedDate
        holder.foodName.text = foodItem.toString().removeSurrounding("[", "]")
        holder.status.text = orderViewModel.status.value.toString()
    }

Currently, I only know how to use substring to design my date format. But it's not my expected. How can I set my Timestamp format?

CodePudding user response：

With this code:

val date = Date(item.date!!.toDate().time)
val newDate = date.toString().substring(0, 16)   date.toString().substring(29, 34)
val formatter = DateTimeFormatter.ofPattern("dd MMM yyyy, HH:mm")
val formattedDate = newDate.format(formatter)

you are taking a date from an item, creating a Date object, then you're adding some string manipulation. Note that toString() on a date could generate different results, based on the system preferences. This is already something you should avoid. Then you're creating a DateTimeFormatter and using it on the newDate, that is a String, so it will not do what you are expecting.

You can obtain what you want simply by using the format on the date and not on the string:

val date = Date(item.date!!.toDate().time)
val formatter = DateTimeFormatter.ofPattern("dd MMM yyyy, HH:mm")
val formattedDate = date.format(formatter)

CodePudding user response：

fun getDateString(seconds: Long, outputPattern: String): String {
        try {
            val dateFormat = SimpleDateFormat(outputPattern, Locale.ENGLISH)
            val calendar = Calendar.getInstance()
            calendar.timeInMillis = seconds * 1000
            val date = calendar.time
            return dateFormat.format(date)
        } catch (e: Exception) {
            Log.e("utils", "Date format", e)
            return ""
        }
    }