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package org.apidesign.apifest08.currency;
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import java.math.BigDecimal;
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import java.math.MathContext;
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import java.math.RoundingMode;
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/** Convertor able to convert amount from one currency to other currency.
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* <p>
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* Conversion method are:
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* <ul>
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* <li>{@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal)} - convert using exchange rate specified in exchange rate provide. <em>Do not try use reverted excahnage rate</em>.
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* <li>{@link #convertWithReversibleRates(ConvertorCurrency, ConvertorCurrency, BigDecimal)} - convert using exchange rate specified in exchange rate provide. <em>Try use reverted excahnage rate</em>.
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* </ul>
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*
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* Exchange rate is provided by {@link ExchangeRateProvider}.
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*/
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public class Convertor {
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private Convertor[] convertors;
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/** Create new <code>Convertor</code> as merge of provided convertors. Merged convertor will use
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* provided convertors to convert between currencies.
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* <p>
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* Only one should be able to provide conversion between currencies. If more than one convertos
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* are able to convert currency, one of conversions will be used (it is not defined which).
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*
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* @since version 2
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* @param convertors Convertor used to create merge-convertor.
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* @return Returns new convertor instance.
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*/
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public static Convertor createConvertorAsMerge(Convertor[] convertors) {
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return new Convertor(convertors);
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}
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boolean remainderAllowed = true; //if false, remained is not allowed (should be true ideally, but can't handle it now)
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ExchangeRateProvider exchangeRateProvider;
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/** Create simle convertor.
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*/
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private Convertor() {
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this.convertors=new Convertor[0];
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}
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/** Create merge convertor.
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*/
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private Convertor(Convertor[] convertors) {
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this.convertors = convertors;
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}
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/**
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* Create new <code>Convertor</code> using <code>ExchangeRateProvider</code>.
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*
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* @param exchangeRateProvider {@link ExchangeRateProvider} used to get exchange rate.
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*
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* @return Returns <code>Convertor</code> which can be used to convert money.
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* @since version1
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*/
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public static Convertor createConvertor(ExchangeRateProvider exchangeRateProvider) {
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Convertor c = new Convertor();
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c.exchangeRateProvider = exchangeRateProvider;
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return c;
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}
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/**
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* Convert <code>amount</code> from <code>fromCurrency</code> to <code>toCurrency</code> as specified
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* in <code>ExchangeRateProvider</code>.
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*
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* @param amount Amount which should be converted. Can't be negative value (can be zero or positive).
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* @return Return <code>ConversionResult</code> which holds conversion result.
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* @since version1
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* @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
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*/
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public ConversionResult convert(BigDecimal amount) {
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return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, false,false);
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}
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/**
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* Convert <code>amount</code> from <code>toCurrency</code> to <code>fromCurrency</code> as specified
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* in <code>ExchangeRateProvider</code>. This is <em>reverted</em> order than suggested by names of currency fields in <code>ExchangeRate</code>.
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*
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* @param amount Amount which should be converted. Can't be negative value (can be zero or positive).
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* @return Return <code>ConversionResult</code> which holds conversion result.
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* @since version1
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* @deprecated since version2. Use {@link #convert(ConvertorCurrency, ConvertorCurrency, BigDecimal) } - explicitly specify conversion currencies.
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*/
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public ConversionResult convertBack(BigDecimal amount) {
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return convertValue(exchangeRateProvider.getFromCurrency(), exchangeRateProvider.getToCurrency(),amount, true,false);
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}
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private ConversionResult convertUsingSimpleConvertor(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, boolean reversibleExRate, BigDecimal amount, boolean convertBack) throws ConversionNotSupportedException, RuntimeException {
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ConversionResult result = new ConversionResult();
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//ExchangeRate rate = exchangeRateProvider.getExchangeRate();
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ExchangeRate rate;
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if (reversibleExRate) {
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rate = exchangeRateProvider.getReversibleExchangeRate(fromCurrency, toCurrency);
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} else {
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rate = exchangeRateProvider.getExchangeRate(fromCurrency, toCurrency);
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}
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if (rate == null) {
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return null;
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}
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int fromFranctionDigits = fromCurrency.getDefaultFractionDigits();
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int toFractionDigits = toCurrency.getDefaultFractionDigits();
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if (toFractionDigits != 2) {
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throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getToCurrency() + " has " + toFractionDigits + " defaultFractionDigits");
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}
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if (fromFranctionDigits != 2) {
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throw new ConvertorException("Can't process currency with defaultFractionDigits!=2, " + exchangeRateProvider.getFromCurrency() + " has " + fromFranctionDigits + " defaultFractionDigits");
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}
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if (amount.signum() == -1) {
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throw new RuntimeException("Can convert only non-negative value, current value is " + amount);
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}
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MathContext context = new MathContext(0, RoundingMode.DOWN);
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BigDecimal from;
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BigDecimal to;
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if (convertBack) {
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//converting in reverted way
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to = rate.getFromValue();
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from = rate.getToValue();
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} else {
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//converting in normal way
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from = rate.getFromValue();
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to = rate.getToValue();
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}
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BigDecimal amountCent = amount.movePointRight(2);
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final BigDecimal multiplied = amountCent.multiply(to, context);
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BigDecimal[] division = multiplied.divideAndRemainder(from, context);
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if (!remainderAllowed && !(BigDecimal.ZERO.equals(division[1]))) {
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throw new RuntimeException("Remained is not allowed - remaining amount is " + division[1] + " cents");
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} else {
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result.setRemainder(BigDecimal.ZERO);
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}
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final BigDecimal converted = division[0].movePointLeft(2);
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result.setConverted(converted);
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//result.setRemainder(...);
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return result;
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}
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private ConversionResult convertValue(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency,BigDecimal amount, boolean convertBack,boolean reversibleExRate) throws RuntimeException {
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//result.setRemainder(...);
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if (convertors.length==0) {
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return convertUsingSimpleConvertor(fromCurrency, toCurrency, reversibleExRate, amount, convertBack);
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} else {
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ConversionResult result = null;
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for (int i = 0;i<convertors.length;i++) {
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Convertor subConvertor = convertors[i];
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result = subConvertor.convertValue(fromCurrency, toCurrency, amount, convertBack, reversibleExRate);
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if (result!=null) {
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break;
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}
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}
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return result;
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}
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}
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/**
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* Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
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* <p>
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* Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
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* This method is using only exchange rate from->to and not trying to use reverted excange rate to->from.
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*
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* @param fromCurrency Source currency to convert from.
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* @param toCurrency Target currency to convert to.
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* @param value Value in source currency which should be converted.
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* @return Return conversion result.
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* @since version2
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* @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code> is not supported.
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*/
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public ConversionResult convert(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
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ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,false);
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if (result==null) {
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//throw new ConversionNotSupportedException("Conversion from " + fromCurrency + " to " + toCurrency + " is not supported");
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throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),false);
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}
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return result;
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}
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/**
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* Convert <code>value</code> from <code>fromCurrency</code> to <code>toCurrency</code>.
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* Exchange rate is provided by exchange rate provider which was specified when Convertor was created.
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* <p>
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* This method is using only exchange rate from->to and if not found, it is trying to use reverted excange rate to->from.
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*
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* @param fromCurrency Source currency to convert from.
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* @param toCurrency Target currency to convert to.
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* @param value Value in source currency which should be converted.
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* @return Return conversion result.
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* @since version2
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* @throws ConversionNotSupportedException If conversion from <code>fromCurrency</code> to <code>toCurrency</code>
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* is not supported and neither conversion from <code>toCurrency</code> to <code>fromCurrency</code> is not supported.
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*/
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public ConversionResult convertWithReversibleRates(ConvertorCurrency fromCurrency, ConvertorCurrency toCurrency, BigDecimal value) {
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ConversionResult result = convertValue(fromCurrency, toCurrency, value, false,true);
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if (result==null) {
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//throw new ConversionNotSupportedException("Neither onversion nor reverted conversion from " + fromCurrency + " to " + toCurrency + " is not supported,");
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throw new ConversionNotSupportedException(fromCurrency.getCurrencyCode(),toCurrency.getCurrencyCode(),true);
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}
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return result;
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}
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}
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