need help in corejava

i m getting the error msg "Exception in thread "main" java.lang.NoSuchMethodError: main" in the following code...please help me solving this problem..

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


public class BanquetBooking implements ActionListener
{

JInternalFrame jif;
JTextField t1,t2,t3,t4,t5,t6;
JButton b1;
JComboBox c1;
public JInternalFrame getFrame()
{

jif = new JInternalFrame("Banquet booking form",false, true, false);

t1= new JTextField(20);
t2= new JTextField(20);


JLabel l1 = new JLabel("Date");
JLabel l2 = new JLabel("Booked by");
JLabel l3 = new JLabel("Ocassion");

c1= new JComboBox();
c1.addItem("Birthday");
c1.addItem("Marriage");
c1.addItem("Anniversary");

JPanel p1= new JPanel();

p1.add(l1);p1.add(t1);p1.add(l2);p1.add(t2);p1.add(l3);p1.add(c1);


p1.setLayout(new GridLayout(3,2));

JPanel p2 = new JPanel();
b1 = new JButton("Book Banquet");
b1.addActionListener(this);

p2.add(b1);

JPanel p3 =new JPanel();

JLabel l4 = new JLabel("Charges :");
t3= new JTextField(20);


p3.add(l4);p3.add(t3);
JPanel mp = new JPanel();
mp.add(p1);mp.add(p2);mp.add(p3);
mp.setLayout(new BoxLayout(mp, BoxLayout.Y_AXIS));

jif.add(mp);
jif.setLayout(new FlowLayout());
return jif;

}
public void actionPerformed(ActionEvent e)
{
if(e.getSource()==b1)
{


Db obj = new Db();
String arr []= new String[4];
arr[0]= t1.getText();
arr[1]= t2.getText();
arr[2]= (String)c1.getSelectedItem();
if(arr[2].equals("Birthday"))
{
arr[3]="10000";
}else if(arr[2].equals("Marriage"))
{
arr[3]="50000";
}else if(arr[2].equals("Anniversary"))
{
arr[3]="20000";
}

String flag=obj.bookBanquet(arr);
t3.setText(flag);
}



}

}