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Java PushbackReader mark() Method with Example

PushbackReader Class mark() method: Here, we are going to learn about the mark() method of PushbackReader Class with its syntax and example.
Submitted by Preeti Jain, on April 20, 2020

PushbackReader Class mark() method

  • mark() method is available in java.io package.
  • mark() method is used to mark the current position in this stream and this method throws an exception during the call.
  • 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 this stream unsupport mark() method.

Syntax:

    public void mark(int r_limit);

Parameter(s):

  • int r_limit – represents 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 // PushbackReader import java.io.*; public class MarkOfPBR { public static void main(String[] args) throws Exception { Reader r_stm = null; PushbackReader pb_r = null; try { // Instantiates Reader and PushbackReader r_stm = new StringReader("Java World!!!!"); pb_r = new PushbackReader(r_stm); // By using read() method isto // read the character from pb_r char ch1 = (char) pb_r.read(); char ch2 = (char) pb_r.read(); char ch3 = (char) pb_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 // pb_r System.out.println("pb_r.mark(1): "); pb_r.mark(1); char ch4 = (char) pb_r.read(); char ch5 = (char) pb_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("pb_r.reset(): "); pb_r.reset(); char ch6 = (char) pb_r.read(); char ch7 = (char) pb_r.read(); char ch8 = (char) pb_r.read(); System.out.println("ch4: " + ch6); System.out.println("ch5: " + ch7); System.out.println("ch6: " + ch8); } catch (Exception ex) { System.out.println("Mark Not Supported"); } finally { // with the help of this block is to // free all necessary resources linked // with the stream if (r_stm != null) { r_stm.close(); if (pb_r != null) { pb_r.close(); } } } } }

Output

ch1: J
ch2: a
ch3: v
pb_r.mark(1): 
Mark Not Supported
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