slip 20 q2

Q2-phonebook
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
class PhoneBook extends JFrame implements ActionListener
{
	JLabel l1,l2,l3,l4;
	JTextField tf1,tf2,tf3,tf4;
	JButton b1,b2,b3,b4;


	Connection con;
	PreparedStatement ps;
	Statement stmt;
	ResultSet rs;



	PhoneBook()
	{

		try
		{
			Class.forName("org.postgresql.Driver");
			con=DriverManager.getConnection("jdbc:postgresql://localhost/tydb","root","");
			if(con==null)
			{
				JOptionPane.showMessageDialog(null,"Unable to connect database : ");
				System.exit(0);
			}
			 stmt=con.createStatement();
                         rs=stmt.executeQuery("select * from phone");


		}
		catch(Exception e)
		{

			JOptionPane.showMessageDialog(null,e);
		}



		setLayout(null);
		l1=new JLabel("Name:");
		l1.setSize(100,30);
		l1.setLocation(10,30);
		add(l1);

		tf1=new JTextField();
		tf1.setSize(200,30);
		tf1.setLocation(150,30);
		add(tf1);

		b1=new JButton("ADD");
		b1.addActionListener(this);
		b1.setSize(150,30);
		b1.setLocation(400,30);
		add(b1);


                l2=new JLabel("Address:");
                l2.setSize(100,30);
                l2.setLocation(10,80);
                add(l2);

                tf2=new JTextField();
                tf2.setSize(200,30);
                tf2.setLocation(150,80);
                add(tf2);

                b2=new JButton("DELETE");
                b2.addActionListener(this);
                b2.setSize(150,30);
                b2.setLocation(400,80);
                add(b2);



                l3=new JLabel("Phone");
                l3.setSize(100,30);
                l3.setLocation(10,130);
                add(l3);

                tf3=new JTextField();
                tf3.setSize(200,30);
                tf3.setLocation(150,130);
                add(tf3);

                b3=new JButton("NEXT");
                b3.addActionListener(this);
                b3.setSize(150,30);
                b3.setLocation(400,130);
                add(b3);



                l4=new JLabel("Email:");
                l4.setSize(100,30);
                l4.setLocation(10,180);
                add(l4);

                tf4=new JTextField();
                tf4.setSize(200,30);
                tf4.setLocation(150,180);
                add(tf4);

                b4=new JButton("PREVIOUS");
                b4.addActionListener(this);
                b4.setSize(150,30);
                b4.setLocation(400,180);
                add(b4);

		setTitle("Q.20 Phone Book Demo");
		setSize(600,500);
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	}
	public void actionPerformed(ActionEvent ae)
	{
		String s=(String)ae.getActionCommand();
		if(s.equals("ADD"))
		{
			String name=tf1.getText();
			String address=tf2.getText();
			String phone=tf3.getText();
			String email=tf4.getText();

			if(name.length()==0 || address.length()==0||phone.length()==0||email.length()==0)
			{
				JOptionPane.showMessageDialog(null,"Can not add data because few Fields are empty");
				return;
			}

			if(phone.charAt(0)=='-')
			{
				 JOptionPane.showMessageDialog(null,"Can not add data because phone number field is negative");
				return;
			}

			try
			{
				ps=con.prepareStatement("insert into phone values(?,?,?,?)");
				ps.setString(1,name);
				ps.setString(2,address);
				ps.setString(3,phone);
				ps.setString(4,email);
				ps.executeUpdate();
				JOptionPane.showMessageDialog(null,"Record is added Succesfully....");
				tf1.setText("");
				tf2.setText("");
				tf3.setText("");
				tf4.setText("");


				stmt=con.createStatement();
				rs=stmt.executeQuery("select * from phone");


			}
			catch(Exception e)
			{
				JOptionPane.showMessageDialog(null,"Problem While Inserting Record...."+e);

			}
		}//ADD


		 if(s.equals("DELETE"))
                {
                        String name=tf1.getText();
                        String address=tf2.getText();
                        String phone=t