Métodos de marca de búfer() en Java con ejemplos

El método mark() de java.nio.Buffer Class se usa para establecer la marca de este búfer en su posición.
Sintaxis: 
 

public Buffer mark()

Valor devuelto: este método devuelve este búfer.
A continuación se muestran los ejemplos para ilustrar el método mark():
Ejemplos 1:
 

// Java program to demonstrate
// mark() method
 
import java.nio.*;
import java.util.*;
 
public class GFG {
 
    public static void main(String[] args)
    {
 
        try {
 
            byte[] barr = { 10, 20, 30, 40 };
 
            // creating object of ByteBuffer
            // and allocating size capacity
            ByteBuffer bb = ByteBuffer.wrap(barr);
 
            // Typecasting ByteBuffer into Buffer
            Buffer bb1 = (Buffer)bb;
 
            // try to set the position at index 2
            bb1.position(2);
 
            // Set this buffer mark position
            // using mark() method
            bb1.mark();
 
            // try to set the position at index 4
            bb1.position(4);
 
            // display position
            System.out.println("position before reset: "
                               + bb1.position());
 
            // try to call reset() to restore
            // to the position we marked
            bb1.reset();
 
            // display position
            System.out.println("position after reset: "
                               + bb1.position());
        }
 
        catch (InvalidMarkException e) {
            System.out.println("new position is less than "
                               + "the position we marked before ");
            System.out.println("Exception throws: " + e);
        }
    }
}

position before reset: 4
position after reset: 2

Ejemplos 2: Para demostrar InvalidMarkException
 

// Java program to demonstrate
// mark() method
 
import java.nio.*;
import java.util.*;
 
public class GFG {
 
    public static void main(String[] args)
    {
 
        try {
 
            byte[] barr = { 10, 20, 30, 40 };
 
            // creating object of ByteBuffer
            // and allocating size capacity
            ByteBuffer bb = ByteBuffer.wrap(barr);
 
            // Typecasting ByteBuffer into Buffer
            Buffer bb1 = (Buffer)bb;
 
            // try to set the position at index 2
            bb1.position(2);
 
            // Set this buffer mark position
            // using mark() method
            bb1.mark();
 
            // try to set the position at index 4
            bb1.position(1);
 
            // display position
            System.out.println("position before reset: "
                               + bb1.position());
 
            // try to call reset() to restore
            // to the position we marked
            bb1.reset();
 
            // display position
            System.out.println("position after reset: "
                               + bb1.position());
        }
 
        catch (InvalidMarkException e) {
            System.out.println("\new position is less than "
                               + "the position we marked before ");
            System.out.println("Exception throws: " + e);
        }
    }
}

position before reset: 1

new position is less than the position we marked before 
Exception throws: java.nio.InvalidMarkException

Referencia: https://docs.oracle.com/javase/9/docs/api/java/nio/Buffer.html#mark–