JDBC sqlite3

import java.io.*;
import java.util.Scanner;
import java.sql.*;

class stdrec{
    String dbDriver;
    String sJdbc;
    String dbUrl;
    String dbName;
    String tbName;

    public stdrec(String namedb, String nametb){
        dbDriver = "org.sqlite.JDBC";
        sJdbc = "jdbc:sqlite";
        dbName = namedb + ".db";
        dbUrl = sJdbc + ":" + dbName;
        tbName = nametb;
    }

    public static void main(String[] args) throws SQLException, ClassNotFoundException {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a DB name: ");
        String dbname = in.nextLine();
        System.out.print("Enter a table name: ");
        String tbname = in.nextLine();

        stdrec dob = new stdrec(dbname, tbname);

        // Loading the driver
        Class.forName(dob.dbDriver);
        System.out.println("Driver Loaded!");

        // Connecting to the database
        Connection con = DriverManager.getConnection(dob.dbUrl);
        System.out.println("Database connected!");

        // Creating statements' link
        Statement stmt = con.createStatement();

        stmt.setQueryTimeout(30);
        stmt.executeUpdate("drop table if exists " + dob.tbName);
        stmt.executeUpdate("create table " + dob.tbName + "(roll text, branch text, fname text, lname text, cgpa text)");


        char c;
        int n;
        String temp;
        ResultSet rs;
        //System.out.print("Continue? y/n: ");
        do{
            System.out.print("1 - Insert\n2 - Update\n3 - Delete\n4 - Show\nOption: ");
            n = in.nextInt();
            in.nextLine();
            switch (n){
                case 1: // Insert
                        System.out.println("Okay!");
                        PreparedStatement inPst = con.prepareStatement("insert into " + dob.tbName + " (roll, branch, fname, lname, cgpa)" + " values(?,?,?,?,?)");
                        System.out.print("Roll: ");
                        inPst.setString(1, in.nextLine());
                        System.out.print("Branch: ");
                        inPst.setString(2, in.nextLine());
                        System.out.print("Name: ");
                        inPst.setString(3, in.nextLine());
                        System.out.print("Surname: ");
                        inPst.setString(4, in.nextLine());
                        System.out.print("CGPA: ");
                        inPst.setString(5, in.nextLine());

                        inPst.executeUpdate();
                        break;

                case 2: // Update
                        System.out.println("Okay!");
                        System.out.println("roll\tbranch\tfname\tlname\tcgpa");
                        PreparedStatement upPst = con.prepareStatement("update " + dob.tbName + " set ? = ? where ? ;");
                        System.out.print("Enter field name: ");
                        temp = in.nextLine();
                        upPst.setString(1, temp);
                        System.out.print("Enter field value: ");
                        temp = in.nextLine();
                        temp = "'" + temp + "'";
                        upPst.setString(2, temp);
                        System.out.print("Enter condition: ");
                        temp = in.nextLine();
                        upPst.setString(3, temp);

                        upPst.executeUpdate();
                        break;

                case 3: //Delete
                        System.out.println("Okay!");
                        System.out.println("roll\tbranch\tfname\tlname\tcgpa");
                        PreparedStatement delPst = con.prepareStatement("delete from " + dob.tbName + " where ? = ? ;");
                        System.out.print("Enter key field: ");
                        temp = in.nextLine();
                        delPst.setString(1, temp);
                        System.out.print("Enter key value: ");
                        temp = in.nextLine();
                        temp = "'" + temp + "'";
                        delPst.setString(2, temp);

                        delPst.executeUpdate();
                        System.out.println("Deleted!");

                        break;
                case 4: // Query / Show
                        System.out.println("Okay!");
                        rs = stmt.executeQuery("select * from " + dob.tbName);

                        while(rs.next())
                            System.out.println(rs.getString(1) + "\t" + rs.getString(2) + "\t" + rs.getString(3) + "\t" + rs.getString(4) + "\t" + rs.getString(5) + "\t");
                        break;

                default:// Defaults
                        System.out.println("Invalid Choice!");
                        break;
            }

            System.out.print("Continue? y/n: ");

        }   while((c = in.next(".").charAt(0)) == 'y');
    }
}