Conversor de cantidades a letra (SPANISH)

import java.math.RoundingMode; import java.text.DecimalFormat; public abstract class ConversorCantidades { private static final String[] UNIDADES = {"", "UN ", "DOS ", "TRES ", "CUATRO ", "CINCO ", "SEIS ", "SIETE ", "OCHO ", "NUEVE ", "DIEZ ", "ONCE ", "DOCE ", "TRECE ", "CATORCE ", "QUINCE ", "DIECISEIS", "DIECISIETE", "DIECIOCHO", "DIECINUEVE", "VEINTE"}; private static final String[] DECENAS = {"VENTI", "TREINTA ", "CUARENTA ", "CINCUENTA ", "SESENTA ", "SETENTA ", "OCHENTA ", "NOVENTA ", "CIEN "}; private static final String[] CENTENAS = {"CIENTO ", "DOSCIENTOS ", "TRESCIENTOS ", "CUATROCIENTOS ", "QUINIENTOS ", "SEISCIENTOS ", "SETECIENTOS ", "OCHOCIENTOS ", "NOVECIENTOS "}; public static String convertNumberToLetter(String number) throws NumberFormatException { return convertNumberToLetter(Double.parseDouble(number)); } public static String convertNumberToLetter(double doubleNumber) throws NumberFormatException { StringBuilder converted = new StringBuilder(); String patternThreeDecimalPoints = "#.###"; DecimalFormat format = new DecimalFormat(patternThreeDecimalPoints); format.setRoundingMode(RoundingMode.DOWN); // formateamos el numero, para ajustarlo a el formato de tres puntos // decimales String formatedDouble = format.format(doubleNumber); doubleNumber = Double.parseDouble(formatedDouble); // Validamos que sea un numero valido if (doubleNumber > 999999999) throw new NumberFormatException( "El numero es mayor de 999'999.999, " + "no es posible convertirlo"); if (doubleNumber < 0) throw new NumberFormatException("El numero debe ser positivo"); String splitNumber[] = String.valueOf(doubleNumber).replace('.', '#') .split("#"); // Descompone el trio de millones int millon = Integer.parseInt(String.valueOf(getDigitAt(splitNumber[0], 8)) + String.valueOf(getDigitAt(splitNumber[0], 7)) + String.valueOf(getDigitAt(splitNumber[0], 6))); if (millon == 1) converted.append("UN MILLON "); else if (millon > 1) converted.append(convertNumber(String.valueOf(millon))).append("MILLONES "); // Descompone el trio de miles int miles = Integer.parseInt(String.valueOf(getDigitAt(splitNumber[0], 5)) + String.valueOf(getDigitAt(splitNumber[0], 4)) + String.valueOf(getDigitAt(splitNumber[0], 3))); if (miles == 1) converted.append("MIL "); else if (miles > 1) converted.append(convertNumber(String.valueOf(miles))).append("MIL "); // Descompone el ultimo trio de unidades int cientos = Integer.parseInt(String.valueOf(getDigitAt( splitNumber[0], 2)) + String.valueOf(getDigitAt(splitNumber[0], 1)) + String.valueOf(getDigitAt(splitNumber[0], 0))); if (cientos == 1) converted.append("UN"); if (millon + miles + cientos == 0) converted.append("CERO"); if (cientos > 1) converted.append(convertNumber(String.valueOf(cientos))); converted.append("PESOS"); // Descompone los centavos int centavos = Integer.parseInt(String.valueOf(getDigitAt( splitNumber[1], 2)) + String.valueOf(getDigitAt(splitNumber[1], 1)) + String.valueOf(getDigitAt(splitNumber[1], 0))); if (centavos == 1) converted.append(" CON UN CENTAVO"); else if (centavos > 1) converted.append(" CON ").append(convertNumber(String.valueOf(centavos))).append("CENTAVOS"); return converted.toString(); } private static String convertNumber(String number) { if (number.length() > 3) throw new NumberFormatException( "La longitud maxima debe ser 3 digitos"); // Caso especial con el 100 if (number.equals("100")) { return "CIEN"; } StringBuilder output = new StringBuilder(); if (getDigitAt(number, 2) != 0) output.append(CENTENAS[getDigitAt(number, 2) - 1]); int k = Integer.parseInt(String.valueOf(getDigitAt(number, 1)) + String.valueOf(getDigitAt(number, 0))); if (k <= 20) output.append(UNIDADES[k]); else if (k > 30 && getDigitAt(number, 0) != 0) output.append(DECENAS[getDigitAt(number, 1) - 2]).append("Y ").append(UNIDADES[getDigitAt(number, 0)]); else output.append(DECENAS[getDigitAt(number, 1) - 2]).append(UNIDADES[getDigitAt(number, 0)]); return output.toString(); } private static int getDigitAt(String origin, int position) { if (origin.length() > position && position >= 0) return origin.charAt(origin.length() - position - 1) - 48; return 0; } }