the compiler does not find any errors but the window doesnt appears when i execute the code.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class BankTEST extends JFrame {

public BankTEST() {
super("a");
Container logincontainer=getContentPane();
logincontainer.setLayout( new FlowLayout() );
JLabel Username=new JLabel("username");
JLabel Password=new JLabel("password");
JTextField UsernameText=new JTextField(10);
JTextField PasswordText=new JPasswordField(10);
JButton Login=new JButton("LOGIN");
logincontainer.add(Username);
logincontainer.add(Password);
logincontainer.add(UsernameText);
logincontainer.add(PasswordText);
logincontainer.setSize( 500, 170 );
logincontainer.setVisible(true);
}
public static void main(String args[]){
BankTEST b=new BankTEST();
b.setDefaultCloseOperation(
JFrame.EXIT_ON_CLOSE );
}

}