Application layer in Java for postgres

main.java

/**
 * @author Somsubhra
 * @author Jigar
 */

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
import java.awt.event.ActionListener;


public class Main {
   static int index = 5; 
   static Connection c = null;
   
   public static void main(String args[]) {
      try {
         Class.forName("org.postgresql.Driver");
         c = DriverManager
            .getConnection("jdbc:postgresql://localhost:5432/organ_portal",
            "postgres", "postgresql");
         c.setAutoCommit(true);
      } catch (Exception e) {
         e.printStackTrace();
         System.err.println(e.getClass().getName()+": "+e.getMessage());
         System.exit(0);
      }
      System.out.println("Opened database organ_portal successfully");
       
       JFrame frame = new JFrame();
       
       frame.setSize(800, 600);
       frame.setResizable(false);
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
       
       JPanel panel = new JPanel();
       
       GridLayout layout = new GridLayout(10, 2);
       panel.setLayout(layout);
       
       JLabel lblName = new JLabel();
       lblName.setText("Name:");
       panel.add(lblName);  
       final JTextField inName = new JTextField();
       panel.add(inName);
       
       JLabel lblAge = new JLabel();
       lblAge.setText("Age:");
       panel.add(lblAge);  
       final JTextField inAge = new JTextField();
       panel.add(inAge);
       
       JLabel lblGen = new JLabel();
       lblGen.setText("Gender:");
       panel.add(lblGen);  
       final JTextField inGen = new JTextField();
       panel.add(inGen);
       
       JLabel lblLoc = new JLabel();
       lblLoc.setText("Location:");
       panel.add(lblLoc);  
       final JTextField inLoc = new JTextField();
       panel.add(inLoc);
       
       JLabel lblMail = new JLabel();
       lblMail.setText("EMail:");
       panel.add(lblMail);  
       final JTextField inMail = new JTextField();
       panel.add(inMail);
       
       JLabel lblPhone = new JLabel();
       lblPhone.setText("Phone:");
       panel.add(lblPhone);  
       final JTextField inPhone = new JTextField();
       panel.add(inPhone);
       
       JLabel lblPass = new JLabel();
       lblPass.setText("password:");
       panel.add(lblPass);  
       final JTextField inPass = new JTextField();
       panel.add(inPass);
       
       JLabel lblBG = new JLabel();
       lblBG.setText("Blood group:");
       panel.add(lblBG);  
       final JTextField inBG = new JTextField();
       panel.add(inBG);
       
       JButton addButton = new JButton();
       addButton.setText("Add Data");
       
       panel.add(addButton);
       
       JButton updButton = new JButton();
       updButton.setText("Update Data");
       panel.add(updButton);
       
       JButton delButton = new JButton();
       delButton.setText("Delete data");
       panel.add(delButton);
       
       class AddButtonListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                System.out.println("Add clicked");
                try {
                   Statement stat = c.createStatement();
                   String sql = "INSERT INTO donor" +
                           "(donor_id, name, age, gen, location," +
                           " email, phone, password, bg) VALUES("+index+",'"+
                           inName.getText()+"',"+inAge.getText()+",'"+inGen.getText()+
                           "','"+inLoc.getText()+"','"+inMail.getText()+"','"+inPhone.getText()+"','"
                           +inPass.getText()+"','"+inBG.getText()+"')";
                   
                   stat.execute(sql);
                   index++;
                }
                catch(Exception ex) {
                    ex.printStackTrace();
                    System.err.println(ex.getMessage());
                }
            }
        
       }
       
       class DelButtonListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                System.out.println("Delete clicked");
                try {
                }
                catch(Exception ex) {
                    System.err.println(ex.getMessage());
                }
            }
       
       }
       
       class UpdButtonListener implements ActionListener {
            public void actionPerformed(ActionEvent e) {
                System.out.println("Update clicked");
                try {
                }
                catch(Exception ex) {
                    System.err.println(ex.getMessage());
                }
            }
       
       }
       
       AddButtonListener addListener = new AddButtonListener();
       addButton.addActionListener(addListener);
       
       DelButtonListener delListener = new DelButtonListener();
       delButton.addActionListener(delListener);
       
       UpdButtonListener updListener = new UpdButtonListener();
       updButton.addActionListener(updListener);
       
       frame.add(panel);
       frame.setVisible(true);
   }
}