A scrollable ResultSet allows you to move both forward and backward through the result set. The Java Database Connectivity (JDBC) API provides support for scrollable ResultSet objects through the Statement and ResultSet interfaces. Here's an example of how to use scrollable ResultSets in JDBC:

import java.sql.*;

public class ScrollableResultSetExample {
    public static void main(String[] args) throws SQLException {
        String url = "jdbc:mysql://localhost:3306/mydb";
        String username = "root";
        String password = "mypassword";

        try (Connection conn = DriverManager.getConnection(url, username, password);
             Statement stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
             ResultSet rs = stmt.executeQuery("SELECT * FROM mytable")) {

            // Get the number of rows in the result set
            rs.last();
            int numRows = rs.getRow();
            rs.beforeFirst();

            // Traverse the result set backwards
            while (rs.previous()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println("ID: " + id + ", Name: " + name);
            }

            // Traverse the result set forwards
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println("ID: " + id + ", Name: " + name);
            }
        }
    }
}

In this example, we first create a Connection object to connect to the database, a Statement object with a scrollable ResultSet type, and a ResultSet object that contains the result set of a query. The TYPE_SCROLL_INSENSITIVE parameter specifies that the ResultSet is scrollable and insensitive to changes in the database, which means that it will not be updated if the underlying data changes. The CONCUR_READ_ONLY parameter specifies that the ResultSet is read-only, which means that we cannot modify the data.

To move the cursor to a specific position, we can use the absolute() or relative() methods of the ResultSet object. The beforeFirst() method moves the cursor to before the first row in the result set, while the last() method moves the cursor to the last row in the result set. The getRow() method returns the current row number, which we can use to get the number of rows in the result set.

Finally, we use a while loop to traverse the result set forwards and print the data in each row. The previous() method is used to move the cursor backwards through the result set, while the next() method is used to move the cursor forwards. We retrieve the data in each row using the getInt() and getString() methods of the ResultSet object.