import java.sql.*;
import java.util.*;

class Passenger{
        public int no;
        public String seatA;
        public String seatB;
        public String seatC;
        public String seatD;

        public Passenger() {
        }
        public Passenger(int no, String seatA, String seatB, String seatC,
                        String seatD) {
                this.no = no;
                this.seatA = seatA;
                this.seatB = seatB;
                this.seatC = seatC;
                this.seatD = seatD;
        }
        public int getNo() {
                return no;
        }
        public void setNo(int no) {
                this.no = no;
        }
        public String getSeatA() {
                return seatA;
        }
        public void setSeatA(String seatA) {
                this.seatA = seatA;
        }
        public String getSeatB() {
                return seatB;
        }
        public void setSeatB(String seatB) {
                this.seatB = seatB;
        }
        public String getSeatC() {
                return seatC;
        }
        public void setSeatC(String seatC) {
                this.seatC = seatC;
        }
        public String getSeatD() {
                return seatD;
        }
        public void setSeatD(String seatD) {
                this.seatD = seatD;
        }
}

continue..

public class AirlineReservation{
        public static void main(String[] args) throws Exception {
                Class.forName("com.mysql.jdbc.Driver").newInstance();
                Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/test","root","root");
                Statement st=con.createStatement();
                List<Passenger> list = new ArrayList<Passenger>();
                list.add(new Passenger(1, "A", "B", "C", "D"));
                list.add(new Passenger(2, "A", "B", "C", "D"));
                list.add(new Passenger(3, "A", "B", "C", "D"));
                list.add(new Passenger(4, "A", "B", "C", "D"));
                list.add(new Passenger(5, "A", "B", "C", "D"));
                list.add(new Passenger(6, "A", "B", "C", "D"));
                list.add(new Passenger(7, "A", "B", "C", "D"));
                for(Passenger s : list){
                System.out.println(s.getNo() + "  " + s.getSeatA() + "  " + s.getSeatB() + "  " + s.getSeatC() + "  " + s.getSeatD());
                }
                Scanner input = new Scanner(System.in);
                System.out.println("Enter Name: ");
                String name=input.nextLine();
                System.out.println("Enter Age: ");
                int age=input.nextInt();
                System.out.println("Enter date of travelling(yyyy-MM-dd): ");
                String dt=input.next();
                System.out.println("Enter seat no(like 1 A): ");
                int num = input.nextInt();
                String sn = input.next();
                for(Passenger s : list){
                if(num == s.getNo()){
                if(sn.equals(s.getSeatA())){
                s.setSeatA("X");
                String ss=Integer.toString(num)+sn;
                int i=st.executeUpdate("insert into airlines(name,age,dateOfTravelling,seat) values('"+name+"',"+age+",'"+dt+"','"+ss+"')");
                System.out.println("Seat "+num+""+sn+" is Reserved");                           
                } else if (sn.equals(s.getSeatB())) {
                s.setSeatB("X");
                String ss=Integer.toString(num)+sn;
                int i=st.executeUpdate("insert into airlines(name,age,dateOfTravelling,seat) values('"+name+"',"+age+",'"+dt+"','"+ss+"')");
                System.out.println("Seat "+num+""+sn+" is Reserved");   
                } else if (sn.equals(s.getSeatC())) {
                s.setSeatC("X");
                String ss=Integer.toString(num)+sn;
                int i=st.executeUpdate("insert into airlines(name,age,dateOfTravelling,seat) values('"+name+"',"+age+",'"+dt+"','"+ss+"')");
                System.out.println("Seat "+num+""+sn+" is Reserved");   
                } else if (sn.equals(s.getSeatD())) {
                s.setSeatD("X");
                String ss=Integer.toString(num)+sn;
                int i=st.executeUpdate("insert into airlines(name,age,dateOfTravelling,seat) values('"+name+"',"+age+",'"+dt+"','"+ss+"')");
                System.out.println("Seat "+num+""+sn+" is Reserved");   
                } else {
                System.out.println("Not Available");
                }
                }
                System.out.println(s.getNo()+"  "+s.getSeatA()+"  "
                +s.getSeatB()+ "  "+s.getSeatC()+"  "+ s.getSeatD());
                }
               }
             }