Swing program to find whether a string is available in Combo Box

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

class JComboBoxDemo extends JFrame
{
JComboBox jcb;
JButton jbtn;
JComboBoxDemo()
{
super("Java with Z");
setSize(500,500);
setDefaultCloseOperation(2);
setLocationRelativeTo(null);
Container c=getContentPane();
c.setLayout(null);

Vector v=new Vector();
v.add("Tom");
v.add("Alex");
v.add("Mike");
v.add("John");

jcb=new JComboBox(v);
jcb.setBounds(100,100,200,30);
c.add(jcb);

jbtn=new JButton("Find Tom");
jbtn.setBounds(100,300,100,30);
jbtn.addActionListener(new ActionListener()
{
public void actionPerformed(java.awt.event.ActionEvent ae)
{
int size=jcb.getItemCount();
for (int i=0;i<size ;i++)
{
String s=jcb.getItemAt(i).toString();
if (s.equalsIgnoreCase("tom"))
{
JOptionPane.showMessageDialog(null,"Found");
}
}

}
});
c.add(jbtn);



setVisible(true);
}
public static void main(String args[] )
{
JComboBoxDemo app=new JComboBoxDemo();
}
}