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Java Reader mark() Method with Example

Reader Class mark() method: Here, we are going to learn about the mark() method of Reader Class with its syntax and example.
Submitted by Preeti Jain, on April 27, 2020

Reader Class mark() method

• mark() method is available in java.io package.
• mark() method is used to set the current position in this stream. When we call reset() method so it reset the stream to the position set by mark() method most recently.
• 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 getting any input/output error or unsupport seek() method.

Syntax:

    public void mark(int r_limit);

Parameter(s):

• int r_limit – represents the limit on the number of characters that can be read before the marks 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 Reader

import java.io.*;

public class MarkOfR {
    public static void main(String[] args) throws Exception {
        Reader r_stm = null;

        try {
            // Instantiates Reader
            r_stm = new StringReader("JavaWorld!!!!");

            // By using read() method isto 
            // read the character from r_stm
            char ch1 = (char) r_stm.read();
            char ch2 = (char) r_stm.read();
            char ch3 = (char) r_stm.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
            // r_stm
            System.out.println("r_stm.mark(1): ");
            r_stm.mark(1);
            char ch4 = (char) r_stm.read();
            char ch5 = (char) r_stm.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("r_stm.reset(): ");
            r_stm.reset();
            char ch6 = (char) r_stm.read();
            char ch7 = (char) r_stm.read();
            char ch8 = (char) r_stm.read();
            char ch9 = (char) r_stm.read();
            char ch10 = (char) r_stm.read();
            char ch11 = (char) r_stm.read();
            char ch12 = (char) r_stm.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);
            System.out.println("ch10: " + ch12);

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

Output

ch1: J
ch2: a
ch3: v
r_stm.mark(1): 
ch4: a
ch5: W
r_stm.reset(): 
ch4: a
ch5: W
ch6: o
ch7: r
ch8: l
ch9: d
ch10: !