Kotlin – Count lines in File

Kotlin – Count lines in File

To count the lines in a file in Kotlin, you can use BufferReader to get the file stream, and then use a while loop to read the lines one by one from the stream, and accumulate the count in a variable.

Steps to count lines in File

Follow these steps to find the number of lines in the file.

  1. Given path to the file in filePath variable.
  2. Create a FileReader object using the file path.
  3. Use BufferReader to get the contents of the file as a stream.
  4. User readLine() method on the BufferReader object in a while loop, and count the lines in the loop.

Kotlin Program to Count Lines in File

In this example program, we shall take a file 'example.txt', and count the lines in it.

The original contents of the 'example.txt' is given below. There are three lines in this file.

Kotlin - Count lines in File - Input file
Original File content


import java.io.BufferedReader
import java.io.FileReader
import java.io.IOException

fun main() {
    val filePath = "example.txt" // Replace with the path to your file
    var lineCount = 0

    try {
        BufferedReader(FileReader(filePath)).use { reader ->
            while (reader.readLine() != null) {
    } catch (e: IOException) {
        println("An exception occurred while reading the file.")
    println("Number of lines in file : $lineCount")


Number of lines in file : 3

There are three lines in given file, and the output reflects the same.


In this Kotlin File Operations tutorial, we have seen how to count the lines in a file using BufferReader, with a detailed step by step process, and example programs.