Java: Read last n lines of a file

Apache commons io library provides 'ReversedLinesFileReader' class to read the file contents in reverse way (Last line first).

Example

try (ReversedLinesFileReader reader = new ReversedLinesFileReader(file, Charset.forName("utf-8"));) {

         while (counter < numLines) {

                  System.out.println(reader.readLine());

                  counter++;

         }

}

App.java

package com.sample.app;

import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;

import org.apache.commons.io.input.ReversedLinesFileReader;

public class App {

 public static void readLastNLines(File file, int numLines) throws IOException {
  int counter = 0;

  try (ReversedLinesFileReader reader = new ReversedLinesFileReader(file, Charset.forName("utf-8"));) {
   while (counter < numLines) {
    System.out.println(reader.readLine());
    counter++;
   }
  }

 }

 public static void main(String args[]) throws IOException {
  File file = new File("/Users/krishna/Documents/test.txt");
  readLastNLines(file, 5);
 }

}

test.txt

Line 1

Line 2

Line 3

Line 4

Line 5

Line 6

Line 7

Line 8

Line 9

Line 10

Line 11

Line 12

Output

Line 12

Line 11

Line 10

Line 9

Line 8

Source code of ReversedLinesFileReader

https://commons.apache.org/proper/commons-io/apidocs/src-html/org/apache/commons/io/input/ReversedLinesFileReader.html

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