DoubleBuffer mark() methods in Java with Examples

The mark() method of java.nio.DoubleBuffer Class is used to mark the current position of this DoubleBuffer as the mark of this buffer.

Syntax:

public DoubleBuffer mark()

Return Value: This method returns this DoubleBuffer after setting the buffer’s mark at the current position.

Below are the examples to illustrate the mark() method:

Examples 1:

// Java program to demonstrate
// mark() method

import java.nio.*;
import java.util.*;

public class GFG {

    public static void main(String[] args)
    {

        try {

            double[] darr = { 10.5, 20.5, 30.5, 40.5 };

            // creating object of DoubleBuffer
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.wrap(darr);

            // try to set the position at index 2
            db.position(2);

            // Set this buffer mark position
            // using mark() method
            db.mark();

            // try to set the position at index 4
            db.position(4);

            // display position
            System.out.println("position before reset: "
                               + db.position());

            // try to call reset() to restore
            // to the position we marked
            db.reset();

            // display position
            System.out.println("position after reset: "
                               + db.position());
        }

        catch (InvalidMarkException e) {
            System.out.println("New position "
                               + "is less than "
                               + "the position "
                               + "marked before ");
            System.out.println("Exception throws: "
                               + e);
        }
    }
}

Output:

position before reset: 4
position after reset: 2

Examples 2: To demonstrate InvalidMarkException

// Java program to demonstrate
// mark() method

import java.nio.*;
import java.util.*;

public class GFG {

    public static void main(String[] args)
    {

        try {

            double[] darr = { 10.5, 20.5, 30.5, 40.5 };

            // creating object of DoubleBuffer
            // and allocating size capacity
            DoubleBuffer db = DoubleBuffer.wrap(darr);

            // try to set the position at index 2
            db.position(2);

            // Set this buffer mark position
            // using mark() method
            db.mark();

            // try to set the position at index 1
            db.position(1);

            // display position
            System.out.println("position before reset: "
                               + db.position());

            // try to call reset() to restore
            // to the position we marked
            db.reset();

            // display position
            System.out.println("position after reset: "
                               + db.position());
        }

        catch (InvalidMarkException e) {
            System.out.println("\nNew position "
                               + "is less than "
                               + "the position "
                               + "marked before ");
            System.out.println("Exception throws: "
                               + e);
        }
    }
}

Output:

position before reset: 1

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

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