Decifrador de numeros a letras [JAVA]

Bueno ya pude hacerlo yo por mi cuenta hehe, lo hice en el jbuilder asi que por eso esta un poco extens de mas [es el ejemplo de una chequera] ahi les va:

package chequera;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import com.borland.jbcl.layout.*;

/**
* Título: 
* Descripción: 
* Copyright: Copyright (c) 2005
* Empresa: 
* @author sin atribuir
* @version 1.0
*/

public class Chequera extends JFrame {
JPanel contentPane;
XYLayout xYLayout1 = new XYLayout();
JLabel jLabel1 = new JLabel();
JLabel jLabel2 = new JLabel();
JLabel jLabel3 = new JLabel();
JLabel jLabel4 = new JLabel();
JLabel jLabel5 = new JLabel();
JTextArea jTextArea1 = new JTextArea();
JButton jButton1 = new JButton();
JTextField jTextField1 = new JTextField();
JTextField jTextField2 = new JTextField();
JTextField jTextField3 = new JTextField();
JTextField jTextField4 = new JTextField();
JLabel jLabel6 = new JLabel();
JButton jButton2 = new JButton();
//Construir el marco
public Chequera() {
enableEvents(AWTEvent.WINDOW_EVENT_MASK);
try {
jbInit();
}
catch(Exception e) {
e.printStackTrace();
}
}

//Inicialización de componentes
private void jbInit() throws Exception {
contentPane = (JPanel) this.getContentPane();
jLabel1.setText("Banco HSBC");
contentPane.setLayout(xYLayout1);
this.setSize(new Dimension(530, 365));
this.setTitle("Chequera");
jLabel2.setText("Fecha:");
jLabel3.setText("Paguese a Nombre de:");
jLabel4.setText("La cantidad de:");
jLabel5.setHorizontalAlignment(SwingConstants.LEFT);
jLabel5.setText("Son:");
jLabel5.setVerticalAlignment(javax.swing.SwingConstants.CENTER);
jButton1.setText("Procesar");
jButton1.addActionListener(new Chequera_jButton1_actionAdapter(this));
jTextField2.setText("");
jTextField1.setText("");
jTextField3.setText("");
jTextField4.setText("");
jTextArea1.setText("");
jLabel6.setVerticalAlignment(javax.swing.SwingConstants.CENTER);
jLabel6.setText("00/100 M.N");
jLabel6.setHorizontalAlignment(SwingConstants.LEFT);
jButton2.setText("Limpiar");
jButton2.addActionListener(new Chequera_jButton2_actionAdapter(this));
contentPane.add(jTextArea1, new XYConstraints(9, 189, 510, 165));
contentPane.add(jButton1, new XYConstraints(162, 144, 81, 26));
contentPane.add(jButton2, new XYConstraints(271, 144, 81, 26));
contentPane.add(jLabel1, new XYConstraints(198, 2, 68, 25));
contentPane.add(jLabel3, new XYConstraints(45, 59, 111, 19));
contentPane.add(jLabel4, new XYConstraints(45, 85, 81, 19));
contentPane.add(jLabel5, new XYConstraints(45, 110, 27, 19));
contentPane.add(jTextField2, new XYConstraints(155, 59, 248, 19));
contentPane.add(jTextField3, new XYConstraints(120, 85, 66, 19));
contentPane.add(jTextField4, new XYConstraints(68, 110, 322, 19));
contentPane.add(jLabel6, new XYConstraints(394, 110, 61, 19));
contentPane.add(jTextField1, new XYConstraints(399, 27, 56, 19));
contentPane.add(jLabel2, new XYConstraints(364, 27, 34, 19));
jTextArea1.setText(" BANCO HSBC"+"\n"+"\n"+
" FECHA:______"+"\n"+"\n"+
" Paguese a nombre de:____________________________________________"+"\n"+"\n"+
" La cantidad de:_________________________________________________"+"\n"+"\n"+
" Son:_________________________________________________ 00/100 M.N");
}

//Modificado para poder salir cuando se cierra la ventana
protected void processWindowEvent(WindowEvent e) {
super.processWindowEvent(e);
if (e.getID() == WindowEvent.WINDOW_CLOSING) {
System.exit(0);
}
}

void jButton1_actionPerformed(ActionEvent e) {
String fecha,nombre,cantidad,lu,ld,lc,lum,ldm,lcm;
int u,d,c,um,dm,cm,cant;
fecha=jTextField1.getText();
nombre=jTextField2.getText();
cant=Integer.parseInt(jTextField3.getText());
if (cant<10 && cant>=0)
jTextField3.setText("00000"+cant);
if (cant<=99 && cant>=10)
jTextField3.setText("0000"+cant);
if (cant<=999 &&cant >=100)
jTextField3.setText("000"+cant);
if (cant<=9999 && cant>=1000)
jTextField3.setText("00"+cant);
if (cant<=99999 && cant>=10000)
jTextField3.setText("0"+cant);
cantidad=jTextField3.getText();

u=Integer.parseInt(cantidad.substring(5,6));
d=Integer.parseInt(cantidad.substring(4,5));
c=Integer.parseInt(cantidad.substring(3,4));
um=Integer.parseInt(cantidad.substring(2,3));
dm=Integer.parseInt(cantidad.substring(1,2));
cm=Integer.parseInt(cantidad.substring(0,1));
switch(u){
case 0: lu="";break;
case 1: lu="un";break;
case 2: lu="dos";break;
case 3: lu="tres";break;
case 4: lu="cuatro";break;
case 5: lu="cinco";break;
case 6: lu="seis";break;
case 7: lu="siete";break;
case 8: lu="ocho";break;
case 9: lu="nueve";break;
default: lu="error";
}
switch(d){
case 0: ld="";break;
case 1: ld="";if (u==0)lu="diez";if(u==1)lu="once";if(u==2)lu="doce";if(u==3)lu="trece";if(u==4)lu="catorce";if(u==5)lu="quince";
if(u==6)lu="dieciseis";if(u==7)lu="diecisiete";if(u==8)lu="dieciocho";if(u==9)lu="diecinueve";break;
case 2: if(u==0)ld="veinte";else ld="veinti";break;
case 3: if(u==0)ld="treinta";else ld="treinta y ";break;
case 4: if(u==0)ld="cuarenta";else ld="cuarenta y ";break;
case 5: if(u==0)ld="cincuenta";else ld="cincuenta y ";break;
case 6: if(u==0)ld="sesenta";else ld="sesnta y ";break;
case 7: if(u==0)ld="setenta";else ld="setenta y ";break;
case 8: if(u==0)ld="ochenta";else ld="ochenta y ";break;
case 9: if(u==0)ld="noventa";else ld="noventa y ";break;
default: ld="error";
}
switch(c){
case 0: lc="";break;
case 1: {
if (d==0 && u==0)
lc="cien";
else
lc="ciento ";break;}
case 2: lc="doscientos ";break;
case 3: lc="trescientos ";break;
case 4: lc="cuatrocientos ";break;
case 5: lc="quinientos ";break;
case 6: lc="seiscientos ";break;
case 7: lc="setecientos ";break;
case 8: lc="ochocientos ";break;
case 9: lc="novecientos ";break;
default: lc="error";}

switch(um){
case 0: lum="";if(dm>0)lum="mil ";if(cm>0)lum="mil ";break;
case 1: lum="unmil ";break;
case 2: lum="dosmil ";break;
case 3: lum="tresmil ";break;
case 4: lum="cuatromil ";break;
case 5: lum="cincomil ";break;
case 6: lum="seismil ";break;
case 7: lum="sietemil ";break;
case 8: lum="ochomil ";break;
case 9: lum="nuevemil ";break;
default: lum="error";}
switch(dm){
case 0: ldm="";break;
case 1: ldm="";if(um==0)lum="diez mil ";if(um==1)lum="once mil ";if(um==2)lum="doce mil ";
if(um==3)lum="trece mil ";if(um==4)lum="catorce mil ";if(um==5)lum="quince mil ";
if(um==6)lum="dieciseis mil ";if(um==7)lum="diecisiete mil ";if(um==8)lum="dieciocho mil ";
if(um==9)lum="diecinueve mil ";break;
case 2: if(u==0)ldm="veinte";else ldm="veinti ";break;
case 3: if(um==0)ldm="treinta";else ldm="treinta y ";break;
case 4: if(um==0)ldm="cuarenta";else ldm="cuarenta y ";break;
case 5: if(um==0)ldm="cincuenta";else ldm="cincuenta y ";break;
case 6: if(um==0)ldm="sesenta";else ldm="sesenta y ";break;
case 7: if(um==0)ldm="setenta";else ldm="setenta y ";break;
case 8: if(um==0)ldm="ochenta";else ldm="ochenta y ";break;
case 9: if(um==0)ldm="noventa";else ldm="noventa y ";break;
default: ldm="error";
}
switch(cm){
case 0: lcm="";break;
case 1: {
if (dm==0 && um==0)
lcm="Cien ";
else
lcm="Ciento ";break;}
case 2: lcm="Doscientos ";break;
case 3: lcm="Trescientos ";break;
case 4: lcm="Cuatrocientos ";break;
case 5: lcm="Quinientos ";break;
case 6: lcm="Seiscientos ";break;
case 7: lcm="Setecientos ";break;
case 8: lcm="Ochocientos ";break;
case 9: lcm="Novecientos ";break;
default: lcm="error";}
if (cant<10 && cant>=0)
jTextField3.setText(""+cant);
if (cant<=99 && cant>=10)
jTextField3.setText(""+cant);
if (cant<=999 &&cant >=100)
jTextField3.setText(""+cant);
if (cant<=9999 && cant>=1000)
jTextField3.setText(""+cant);
if (cant<=99999 && cant>=10000)
jTextField3.setText(""+cant);
cantidad=jTextField3.getText();

jTextArea1.setText(" BANCO HSBC"+"\n"+"\n"+
" FECHA:"+fecha+
"\n"+"\n"+" Paguese a nombre de: "+nombre+"\n"+"\n"+
" La cantidad de: $"+cantidad+"\n"+"\n"+
" Son: "+lcm+ldm+lum+lc+ld+lu+" 00/100 M.N");
jTextField4.setText(lcm+ldm+lum+lc+ld+lu);
}

public void jButton2_actionPerformed(ActionEvent e) {
jTextField1.setText(" ");
jTextField2.setText(" ");
jTextField3.setText("");
jTextField4.setText(" ");
jTextArea1.setText(" BANCO HSBC"+"\n"+"\n"+
" FECHA:______"+"\n"+"\n"+
" Paguese a nombre de:____________________________________________"+"\n"+"\n"+
" La cantidad de:_________________________________________________"+"\n"+"\n"+
" Son:__________________________________________________00/100 M.N");
}
}

class Chequera_jButton2_actionAdapter
implements ActionListener {
private Chequera adaptee;
Chequera_jButton2_actionAdapter(Chequera adaptee) {
this.adaptee = adaptee;
}

public void actionPerformed(ActionEvent e) {
adaptee.jButton2_actionPerformed(e);
}
}

class Chequera_jButton1_actionAdapter implements java.awt.event.ActionListener {
Chequera adaptee;

Chequera_jButton1_actionAdapter(Chequera adaptee) {
this.adaptee = adaptee;
}
public void actionPerformed(ActionEvent e) {
adaptee.jButton1_actionPerformed(e);
}
}