Reader mark(int) in Java

mark(int): This method is available in the java.io.Reader class of Java.

Syntax:

void java.io.Reader.mark(int readAheadLimit) throws IOException

This method takes one argument. This method marks the present position in the stream.

Parameters: One parameter is required for this method.

readAheadLimit: Limit the number of characters that may be read while still preserving the mark.

Returns: NA

Throws:

1. IOException - If the stream does not support mark(), or if some other I/O error occurs.

Approach 1: When no exception

Java

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

public class Readermark {
    public static void main(String[] args) throws IOException {

        Reader reader = new StringReader("HELLO");

        int readAheadlimit = 10;
        reader.mark(readAheadlimit);

        System.out.println("Successfully mark the read limit");
        reader.close();

    }
}

Output:

Successfully mark the read limit

Approach 2: IOException

Java

package com.Reader;

import java.io.FileReader;
import java.io.IOException;
import java.io.Reader;

public class Readermark {
    public static void main(String[] args) throws IOException {

        Reader reader = new FileReader("D:\\hello.txt");

        int readAheadlimit = 10;
        reader.mark(readAheadlimit);

        System.out.println("Successfully mark the read limit");
        reader.close();

    }
}

Output:

Exception in thread "main" java.io.IOException: mark() not supported
	at java.base/java.io.Reader.mark(Reader.java:324)
	at com.Reader.Readermark.main(Readermark.java:13)

Some other methods of Reader

close(): This method closes the stream and releases any system resources associated with it.

mark(int): This method marks the present position in the stream.

markSupported(): This method tells whether this stream supports the mark() operation. 

Reader.nullReader(): This method returns a new Reader that reads no characters.

read(): This method reads a single character.

read(char[]): This method reads characters into an array.

read(CharBuffer): This method attempts to read characters into the specified character buffer.

read(char[], int, int): This method reads characters into a portion of an array.

ready(): This method tells whether this stream is ready to be read.

reset(): This method resets the stream.

skip(long): This method skips characters.

transferTo(Writer): This method reads all characters from this reader and writes the characters to the given writer in the order that they are read.