Java.io.PushbackReader.mark() Method

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Description

The java.io.PushbackReader.mark(int readAheadLimit) method marks the present position in the stream. The mark for class PushbackReader always throws an exception.

Declaration

Following is the declaration for java.io.PushbackReader.mark() method.

public void mark(int readAheadLimit)

Parameters

readAheadLimit − Limit on the number of characters that may be read while still preserving the mark. After reading this many characters, attempting to reset the stream may fail.

Return Value

This method does not return a value.

Exception

IOException − Always, since mark is not supported.

Example

The following example shows the usage of java.io.PushbackReader.mark() method.

package com.tutorialspoint;

import java.io.*;

public class PushbackReaderDemo {
   public static void main(String[] args) {      
      String s = "Hello World";

      // create a new StringReader
      StringReader sr = new StringReader(s);

      // create a new PushBack reader based on our string reader
      PushbackReader pr = new PushbackReader(sr, 20);
      
      try {
         // read the first five chars
         for (int i = 0; i < 5; i++) {
            char c = (char) pr.read();
            System.out.print("" + c);
         }

         // change line
         System.out.println();

         // mark the current position results in exception
         pr.mark(5);

         // close the stream
         pr.close();
      } catch (IOException ex) {
         ex.printStackTrace();
      }
   }
}

Let us compile and run the above program, this will produce the following result −

Hello
java.io.IOException: mark/reset not supported