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So I have thousands of coordinates that i need to plot and one of the best method i know is by saving the coordinates as .txt in asset folder and then pull it by using

val json_string = application.assets.open(file_name).bufferedReader().use{it.readText()}

But when the file is pulled, it read the file as a string, despite the file is saved in array format such as follow:

"97.951476367000055,3.155017079000061","97.951800004000063,3.154406602000051","97.949325673000033,3.156145963000029","97.948721732000081,3.15657051200003","97.948646156000052,3.156623638000042","97.947494978000066,3.15786896100002","97.94724135000007,3.158143331000076","97.947000011000057,3.158404405000056","97.946790649000036,3.158630887000072","97.946272953000062,3.15919092200005","97.945702608000033,3.15980791000004","97.945553326000038,3.159969400000023","97.944601930000033,3.160998592000055","97.944409762000078,3.161206474000039"....

I want to read the asset in an array format, for example, it is divided by comma and grouped by quotes, for example:

  • "97.951476367000055,3.155017079000061"
  • "97.951800004000063,3.154406602000051"
  • "97.949325673000033,3.156145963000029"
  • and so on...

How can I read this .txt file asset as string array or ArrayList< String > format in Kotlin?

Thanks!

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3
  • I would think a far better way would be to store it as doubles (write them to the file as bytes). About 9 times smaller file that would be much faster to read and write. But it depends on the precision you need. Commented Oct 13, 2023 at 13:36
  • Use split() to divide the string into substrings based on the delimiter. Commented Oct 13, 2023 at 13:39
  • despite the file is saved in array format such as follow: That is no array format. It is just one text line with comma separated values. You better make a csv/txt file with lines. A line for every location. And it is no json string either. Commented Oct 13, 2023 at 13:40

2 Answers 2

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Create a model like below

data class Coordinate(val latitude: String, val longitude: String)

// Function to read coordinates from the asset file and convert to ArrayList

fun readCoordinatesFromAsset(context: Context, assetFileName: String): ArrayList<String> { val gson = Gson() val arrayList = ArrayList<String>() try { context.assets.open(assetFileName).use { inputStream -> val reader = InputStreamReader(inputStream) val coordinates = gson.fromJson(reader, ArrayList::class.java) // Convert the ArrayList of Coordinate objects to an ArrayList of strings for (coordinate in coordinates) { arrayList.add(coordinate.toString()) } } } catch (e: Exception) { e.printStackTrace() } return arrayList }

Your text file should be like the below format

coordinate.txt

[ "97.951476367000055,3.155017079000061", "97.951800004000063,3.154406602000051", "97.949325673000033,3.156145963000029", "97.948721732000081,3.15657051200003", "97.948646156000052,3.156623638000042", "97.947494978000066,3.15786896100002", "97.94724135000007,3.158143331000076", "97.947000011000057,3.158404405000056", "97.946790649000036,3.158630887000072", "97.946272953000062,3.15919092200005", "97.945702608000033,3.15980791000004", "97.945553326000038,3.159969400000023", "97.944601930000033,3.160998592000055", "97.944409762000078,3.161206474000039" ]

You can call the method as

val resulArray: ArrayList<String> =readCoordinatesFromAsset(this,"coordinate.txt")
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It works smoothly! Great!
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You can try something like this, see the code below.

https://pl.kotl.in/NQQdTW6m4?theme=darcula

Code for the problem

Click on the link above, to test and run the code, also you can define your own model class, instead of the Pair() which I have use to demonstrate in this case. Feel free to improve it!

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