please help me in creating a form using Swing.

I am creating a form using swing through coding (not using netbeans).
Now in the form I have one JComboBox
of Country and other of State. Now I want it in such a way that when
I select a country from the Country JComboBox ,the corresponding
states
automatically appears in the State JComboBox. Please help.
I hope I've put up my query clearly.
Still learning java!!:)
 I am posting here a part of my coding related to my problem.
===============================================
import javax.swing.*;
import java.awt.*;
class Design extends JFrame
{
 public Design()
 {
  super("Tenant Form");
  setLayout(new FlowLayout());

  GridBagConstraints gbc=new GridBagConstraints();
  gbc.insets=new Insets(2,2,2,2);
  gbc.anchor=GridBagConstraints.WEST;

  JPanel jp21=new JPanel();
  jp21.setBorder(new TitledBorder("Address Of Landlord Property"));
  jp21.setLayout(new GridBagLayout());

  JLabel l11=new JLabel("Property/House/Building Address");
  gbc.gridx=0;
  gbc.gridy=0;
  jp21.add(l11,gbc);

  JTextArea ta11=new JTextArea(3,15);
  ta11.setLineWrap(true);
  int v=ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED;
  int h=ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED;
  JScrollPane scroll11=new JScrollPane(ta11,v,h);
  gbc.gridx=1;
  jp21.add(scroll11);
  jp21.add(ta11,gbc);

  JLabel l21=new JLabel("Land Mark");
  gbc.gridx=0;
  gbc.gridy=1;
  gbc.ipady=0;
  gbc.gridheight=1;
  jp21.add(l21,gbc);

  JTextField tf21=new JTextField(15);
  gbc.gridx=1;
  gbc.gridy=1;
  jp21.add(tf21,gbc);

  JLabel l31=new JLabel("Country");
  gbc.gridx=0;
  gbc.gridy=2;
  jp21.add(l31,gbc);

  JComboBox c11=new JComboBox();
  c11.addItem("India");
  c11.addItem("US");
  c11.addItem("Australia");
  gbc.gridx=1;
  gbc.gridy=2;
  jp21.add(c11,gbc);

  JLabel l41=new JLabel("State");
  gbc.gridx=0;
  gbc.gridy=3;
  jp21.add(l41,gbc);

  JComboBox c21=new JComboBox();
  c21.addItem("Rajasthan");
  c21.addItem("Delhi");
  c21.addItem("Maharastra");
  gbc.gridx=1;
  gbc.gridy=3;
  jp21.add(c21,gbc);

  JLabel l51=new JLabel("District");
  gbc.gridx=0;
  gbc.gridy=4;
  jp21.add(l51,gbc);

  JComboBox c31=new JComboBox();
  c31.addItem("jaipur");
  c31.addItem("ajmer");
  c31.addItem("alwar");
  gbc.gridx=1;
  gbc.gridy=4;
  jp21.add(c31,gbc);

  JLabel l61=new JLabel("City/Town");
  gbc.gridx=0;
  gbc.gridy=5;
  jp21.add(l61,gbc);

  JTextField tf31=new JTextField(15);
  gbc.gridx=1;
  gbc.gridy=5;
  jp21.add(tf31,gbc);

  JLabel l71=new JLabel("Police District");
  gbc.gridx=0;
  gbc.gridy=6;
  jp21.add(l71,gbc);

  JComboBox c41=new JComboBox();
  c41.addItem("Jaipur");
  c41.addItem("Alwar");
  c41.addItem("Ajmer");
  gbc.gridx=1;
  gbc.gridy=6;
  jp21.add(c41,gbc);

  JLabel l81=new JLabel("Police Circle");
  gbc.gridx=0;
  gbc.gridy=7;
  jp21.add(l81,gbc);

  JComboBox c51=new JComboBox();
  c51.addItem("India");
  c51.addItem("US");
  c51.addItem("Australia");
  gbc.gridx=1;
  gbc.gridy=7;
  jp21.add(c51,gbc);

  JLabel l91=new JLabel("Police station");
  gbc.gridx=0;
  gbc.gridy=8;
  jp21.add(l91,gbc);

  JComboBox c61=new JComboBox();
  c61.addItem("Bani Park");
  c61.addItem("Raja Park");
  c61.addItem("Malviya Nagar");
  gbc.gridx=1;
  gbc.gridy=8;
  jp21.add(c61,gbc);

  JLabel l101=new JLabel("Pin No.");
  gbc.gridx=0;
  gbc.gridy=9;
  jp21.add(l101,gbc);

  JTextField tf41=new JTextField(15);
  gbc.gridx=1;
  gbc.gridy=9;
  jp21.add(tf41,gbc);

  JLabel l111=new JLabel("Phone No.(R)");
  gbc.gridx=0;
  gbc.gridy=10;
  jp21.add(l111,gbc);

  JTextField tf51=new JTextField(15);
  gbc.gridx=1;
  gbc.gridy=10;
  jp21.add(tf51,gbc);
  add(jp21);
  }
}

public class Project
{
 public static void main(String args[]) //main method
for the program
 {
  Design tabbedwin= new Design();
  tabbedwin.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  tabbedwin.setSize(900,700);
  tabbedwin.setVisible(true);
 }

}

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The actual coding consist of 6 tabs each with same type of several
panels. Here I need to connect country , state and district
respectively.