Codigo Fuente Gasolina Java

import javax.swing.*;

import java.awt.*;

public class E11Gasolina extends JFrame
{
private JLabel lblGasolina;
private JLabel lblLitros;
private JLabel lblImporte;
private JLabellblCosto;
private JTextField txtLitros;
private JTextField txtImporte;
private JTextField txtCosto;
private JProgressBar jpbGasolina;
private java.awt.event.KeyListener kl;
privatejava.awt.event.ActionListener al;
private double costo;
private Timer tiempo;
private int contador;
private JTextField auxTF;
private double auxCosto;
public E11Gasolina()
{this.setSize(340, 300);
this.setLocationRelativeTo(null);
this.initComponents();
costo = Double.parseDouble(this.txtCosto.getText());
this.initListeners();
}

private voidinitComponents()
{
this.getContentPane().setLayout(null);
//lblGasolina
this.lblGasolina = new JLabel("Gasolina");
this.lblGasolina.setBounds(42, 10, 100, 20);this.lblGasolina.setForeground(java.awt.Color.BLUE);
this.getContentPane().add(lblGasolina);
//jpbGasolina
this.jpbGasolina = new JProgressBar(JProgressBar.VERTICAL);
this.jpbGasolina.setBounds(20, 40, 100,200);
this.jpbGasolina.setMaximum(1000);
this.jpbGasolina.setValue(1000);
this.jpbGasolina.setForeground(java.awt.Color.CYAN);
this.getContentPane().add(jpbGasolina);
//lblLitrosthis.lblLitros = new JLabel("Litros");
this.lblLitros.setBounds(210, 10, 100, 20);
this.getContentPane().add(lblLitros);
//txtLitros
this.txtLitros = new JTextField();this.txtLitros.setBounds(180, 40, 100, 20);
this.txtLitros.setHorizontalAlignment(JTextField.RIGHT);
this.getContentPane().add(txtLitros);
//lblImporte
this.lblImporte = new JLabel("Importe");this.lblImporte.setBounds(205, 70, 100, 20);
this.getContentPane().add(lblImporte);
//txtImporte
this.txtImporte = new JTextField();
this.txtImporte.setBounds(180, 100, 100, 20);...