public class Gui13  extends JFrame{
    JLabel l1;
    JButton b1,b2;
    JTextField cantidad;

    public Gui13(){
        super("Conversor Euros-pesetas");
        setLayout(new FlowLayout());

        b1=new JButton("A euros");
        b2=new JButton("A pesetas");
        cantidad = new JTextField(10);
        l1=new JLabel("Texto");
        add(l1);
        add(cantidad);
        add(b1);
        add(b2);

        b1.addActionListener(new OyenteBoton());
        b2.addActionListener(new OyenteBoton());

        b1.setActionCommand("E");
        b2.setActionCommand("P");

        setSize(400,100);
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }


    public static void main(String[] args) {
        Gui13 ventana = new Gui13();

    }

    class OyenteBoton implements ActionListener{
        @Override
        public void actionPerformed(ActionEvent e) {
           Float f = new Float(cantidad.getText());
           float valor = f.floatValue();

           String s = (String) e.getActionCommand();

           if (s.equals("E")){
               valor = (float) (valor/166.321);
           } else if (s.equals("P")){
               valor = (float) (valor*166.321);
           }
           cantidad.setText(Float.toString(valor));
        }
    }

}