Mã:
import java.awt.Choice;
import java.awt.Rectangle;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.JFrame;
public class nhan extends JFrame
{
	// thong tin tai khoan
	JLabel thongtin=new JLabel();
	// dang nhap
	JLabel tendangnhap=new JLabel();
	JTextField dangnhap=new JTextField();
	JButton kiemtra= new JButton();
	// pass 
	JLabel pass=new JLabel();
	JTextField khungpass=new JTextField();
	// xac nhan pass
	JLabel xnpass=new JLabel();
	JTextField khungxnpass = new JTextField();
	// thong tin ca nhan
	JLabel canhan=new JLabel();
	// ten
	JLabel ten=new JLabel();
	JTextField khungten=new JTextField();
	// gioi tinh
	JLabel giotinh=new JLabel();
	JRadioButton nutgioitinh=new JRadioButton();
	ButtonGroup gop= new ButtonGroup();
	// ngay sinh
	JLabel ngaysinh = new JLabel();
	Choice ngay = new Choice();
	Choice thang = new Choice();
	Choice nam = new Choice();
	//ban song tai 
	JLabel diachi = new JLabel();
	Choice songtai=new Choice();
	// dieu khoan
	JCheckBox dieukhoan = new JCheckBox();
	/ut dang ki
	JButton bdk=new JButton();
	// nut cancel
	JButton thoat = new JButton();
    public nhan() {
    	this.getContentPane().setLayout(null);
    	thongtin.setBounds(new Rectangle(50,50,150,50));
    	thongtin.setText("Thong tin tai khoan ");
    	this.getContentPane().add(thongtin);
    	
    	tendangnhap.setBounds(new Rectangle(100,80,100,20));
    	tendangnhap.setText("Ten Dang Nhap");
    	this.getContentPane().add(tendangnhap);
    	dangnhap.setBounds(new Rectangle(230,80,150,20));
    	this.getContentPane().add(dangnhap);
    	
    	pass.setBounds(new Rectangle(100,100,100,20));
    	pass.setText("Password ");
    	this.getContentPane().add(pass);
    	
    	khungpass.setBounds(new Rectangle(230,100,150,20));
    	this.getContentPane().add(khungpass);
    
    	
    	xnpass.setBounds(new Rectangle(100,120,150,20));
    	xnpass.setText("Xac Nhan Password");
    	this.getContentPane().add(xnpass);
    	khungxnpass.setBounds(new Rectangle(230,120,150,20));
    	this.getContentPane().add(khungxnpass);
    	
    	canhan.setBounds(new Rectangle(50,130,150,50));
    	canhan.setText("Thong Tin Ca Nhan");
    	this.getContentPane().add(canhan);
    	
    	ten.setBounds(new Rectangle(100,160,100,20));
    	ten.setText("Ho va Ten");
    	this.getContentPane().add(ten);
    	
    	khungten.setBounds(new Rectangle(230,160,150,20));
    	this.getContentPane().add(khungten);
    	
    	ngaysinh.setBounds(new Rectangle(100,180,100,20));
    	ngaysinh.setText("Ngay Sinh");
    	this.getContentPane().add(ngaysinh);
    	?????
    	????
    }
public static void main (String[] args) {
		nhan f=new nhan();
		f.setSize(500,400);
		f.show();
}   
}
thêm vào 1 choice ngay sinh
vd :[ngay] [thang] [nam] click vao ngày thì có 1 danh sách tu ngày 1 đến 30,thang thì 1-> 12, nam thi 1990-> 1993 thôi,