I wonder what your code is...
Sounds like a problem with your ComboboxModel.

Here is my code..just try this one....
you will get correct out put ..
but if u change that item name means
abc1
abc2
abc3
abc4
abc5


to

abc
abc
abc
abc
abc

i cant get the selected index value .. please someone giveme solution








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

public class combo extends JFrame
{
private JComboBox jComboBox1;
private JPanel contentPane;
JTextField jtf=new JTextField();
public combo()
{
super();
initializeComponent();
this.setVisible(true);
}

private void initializeComponent()
{
jComboBox1 = new JComboBox();
contentPane = (JPanel)this.getContentPane();

jComboBox1.addItem("abc1");
jComboBox1.addItem("abc2");
jComboBox1.addItem("abc3");
jComboBox1.addItem("abc4");
jComboBox1.addItem("abc5");

jComboBox1.addItemListener(new cbx2dDtime());
contentPane.setLayout(null);
addComponent(contentPane, jComboBox1, 135,70,100,22);
addComponent(contentPane, jtf, 164,110,250,22);
this.setTitle("combo - extends JFrame");
this.setLocation(new Point(0, 0));
this.setSize(new Dimension(390, 300));
}

private void addComponent(Container container,Component c,int x,int y,int width,int height)
{
c.setBounds(x,y,width,height);
container.add(c);
}

public class cbx2dDtime implements ItemListener
{
public void itemStateChanged(ItemEvent ie)
{
int sitem=jComboBox1.getSelectedIndex();
jtf.setText("Selected index "+sitem);
}
}

public static void main(String[] args)
{
JFrame.setDefaultLookAndFeelDecorated(true);
JDialog.setDefaultLookAndFeelDecorated(true);
try
{
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
}
catch (Exception ex)
{
System.out.println("Failed loading L&F: ");
System.out.println(ex);
}
new combo();
}
}

guys Help me out.......I got confused with this problem...

it's quite simple.
The JComboBox check whether the item you selected is in its list of items.
If the same item is in the list more than once (as in your case) it will simply return one of them (and almost certainly, based on my knowledge of the actual implementation of the class, the first one of those items).
It simply can't distinguish between them, as they are indeed all identical.
To change that create a custom ComboBoxModel and assign that to the JComboBox. In that make sure that the items are unique.