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Java LineNumberReader mark() Method with Example

LineNumberReader Class mark() method: Here, we are going to learn about the mark() method of LineNumberReader Class with its syntax and example.
Submitted by Preeti Jain, on April 16, 2020

LineNumberReader Class mark() method

• mark() method is available in java.io package.
• mark() method is used to set the current position in this LineNumberReader stream and whenever we call to reset() so it will reset the stream to the position set by the most recent call of mark() method.
• mark() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
• mark() method may throw an exception at the time of marking the stream.
  IOException: This exception may throw when the given parameter is not valid.

Syntax:

    public int mark();

Parameter(s):

• int r_limit – represents the limit on the number of characters that can be read before the mark gets invalid.

Return value:

The return type of the method is void, it returns nothing.

Example:

// Java program to demonstrate the example 
// of void mark(int r_limit) method of 
// LineNumberReader

import java.io.*;

public class MarkOfLNR {
 public static void main(String[] args) throws Exception {
  FileReader fr_stm = null;
  LineNumberReader line_r = null;
  int val = 0;

  try {
   // Instantiates FileReader and LineNumberReader
   fr_stm = new FileReader("D:\\includehelp.txt");
   line_r = new LineNumberReader(fr_stm);

   // By using read() method isto 
   // read the character from line_r
   char ch1 = (char) line_r.read();
   char ch2 = (char) line_r.read();
   char ch3 = (char) line_r.read();

   System.out.println("ch1: " + ch1);
   System.out.println("ch2: " + ch2);
   System.out.println("ch3: " + ch3);

   // By using mark() method isto
   // set the current position in this
   // line_r

   System.out.println("line_r.mark(0): ");
   line_r.mark(0);
   char ch4 = (char) line_r.read();
   char ch5 = (char) line_r.read();

   System.out.println("ch4: " + ch4);
   System.out.println("ch5: " + ch5);

   // By using reset() method isto
   // reset the stream to the position 
   // set by the call mark() method

   System.out.println("line_r.reset(): ");
   line_r.reset();
   char ch6 = (char) line_r.read();
   char ch7 = (char) line_r.read();
   char ch8 = (char) line_r.read();
   char ch9 = (char) line_r.read();
   char ch10 = (char) line_r.read();
   char ch11 = (char) line_r.read();

   System.out.println("ch4: " + ch6);
   System.out.println("ch5: " + ch7);
   System.out.println("ch6: " + ch8);
   System.out.println("ch7: " + ch9);
   System.out.println("ch8: " + ch10);
   System.out.println("ch9: " + ch11);

  } catch (Exception ex) {
   System.out.println(ex.toString());
  } finally {
   // with the help of this block is to
   // free all necessary resources linked
   // with the stream
   if (fr_stm != null) {
    fr_stm.close();

    if (line_r != null) {
     line_r.close();
    }
   }
  }
 }
}

Output

ch1: J
ch2: A
ch3: V
line_r.mark(0):
ch4: A
ch5: W
line_r.reset():
ch4: A
ch5: W
ch6: O
ch7: R
ch8: L
ch9: D