JComboBoxDemo.java

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

public class JComboBoxDemo {
    JFrame f = new JFrame("JComboBox Demo");
    JLabel l1 = new JLabel();
    JComboBox cb1;

    void makeMyWindow() {
        JLabel l2 = new JLabel("Select Your Birth Month");
        l2.setBounds(50, 50, 200, 30);
        l1.setBounds(50, 300, 200, 20);
        //array to store months
        String months[] = {"January", "February", "March",
                "April", "May", "June", "July", "August",
                "September", "October", "November", "December"};
        //creating object of handler class
        MyHandler h = new MyHandler();
        //comboBox
        cb1 = new JComboBox(months);
        cb1.setBounds(50, 100, 90, 20);
        cb1.addActionListener(h);
        f.add(cb1);
        f.add(l1);
        f.add(l2);
        f.setLayout(null);
        f.setSize(400, 400);
        f.setVisible(true);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    //inner class to handel event
    class MyHandler implements ActionListener {
        public void actionPerformed(ActionEvent ae) {
            String m = (String) cb1.getSelectedItem();
            l1.setText("Your Birth Month is " + m);
        }
    }

    public static void main(String[] args) {
        JComboBoxDemo cmb = new JComboBoxDemo();
        cmb.makeMyWindow();
    }
}