1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/task2/solution10/src/org/apidesign/apifest08/currency/MultiCurrencyConstantRateConverter.java	Wed Oct 01 10:43:05 2008 +0200
     1.3 @@ -0,0 +1,71 @@
     1.4 +package org.apidesign.apifest08.currency;
     1.5 +
     1.6 +import java.util.*;
     1.7 +
     1.8 +final class MultiCurrencyConstantRateConverter implements CurrencyConverter {
     1.9 +
    1.10 +	private final Map<Currency, Double> rates;
    1.11 +
    1.12 +	public MultiCurrencyConstantRateConverter(Map<Currency, Double> rates) {
    1.13 +		this.rates = rates;
    1.14 +	}
    1.15 +
    1.16 +	/**
    1.17 +	 * This is convenience method for convert(Currency.getInstance(from), Currency.getInstance(to)).
    1.18 +	 *
    1.19 +	 * @param value that should be converted form one currency to the other
    1.20 +	 * @param from  ISO-4217 code of the currency of the value provided
    1.21 +	 * @param to	ISO-4212 code of the currency to which the value should be converted
    1.22 +	 *
    1.23 +	 * @return value expressed in the target value
    1.24 +	 *
    1.25 +	 * @throws IllegalArgumentException if any of the arguments is not a valid ISO code
    1.26 +	 * @throws CurrencyConversionException
    1.27 +	 *                                  if the conversion cannot be performed with desired parameters, for
    1.28 +	 *                                  example the exchange rates are not current, connection to exchange rates
    1.29 +	 *                                  provider is not available
    1.30 +	 * @throws NullPointerException	 if any of the specified currency ISO codes is null
    1.31 +	 */
    1.32 +	// this method is provided to ensure future compatibility for converters supporting more than 2 currencies
    1.33 +	//		- simpler methods with fewer arguments would make using such converters less intuitive
    1.34 +	@Override
    1.35 +	public double convert(double value, /*@NotNull*/ String from, /*@NotNull*/ String to)
    1.36 +			throws CurrencyConversionException, NullPointerException, IllegalArgumentException {
    1.37 +		return convert(value, Currency.getInstance(from), Currency.getInstance(to));
    1.38 +	}
    1.39 +
    1.40 +	/**
    1.41 +	 * Converts the specified value from one currency (from) to target currency (to).
    1.42 +	 *
    1.43 +	 * @param value that should be converted form one currency to the other
    1.44 +	 * @param from  ISO-4217 code of the currency of the value provided
    1.45 +	 * @param to	ISO-4212 code of the currency to which the value should be converted
    1.46 +	 *
    1.47 +	 * @return value expressed in the target value
    1.48 +	 *
    1.49 +	 * @throws IllegalArgumentException if any of the arguments is not a valid ISO code
    1.50 +	 * @throws CurrencyConversionException
    1.51 +	 *                                  if the conversion cannot be performed with desired parameters, for
    1.52 +	 *                                  example the exchange rates are not current, connection to exchange rates
    1.53 +	 *                                  provider is not available
    1.54 +	 * @throws NullPointerException	 if any of the specified currency ISO codes is null
    1.55 +	 */
    1.56 +	@Override
    1.57 +	public double convert(double value, /*@NotNull*/ Currency from, /*@NotNull*/ Currency to)
    1.58 +			throws CurrencyConversionException, NullPointerException {
    1.59 +
    1.60 +		// this is not necessary, but we let users know that nulls are not allowed here - should be handled by annotations
    1.61 +		if (from == null || to == null)
    1.62 +			throw new NullPointerException("One of the specified currencies in null");
    1.63 +
    1.64 +		Double fromRate = rates.get(from);
    1.65 +		Double toRate = rates.get(to);
    1.66 +
    1.67 +		if (fromRate == null)
    1.68 +			throw new CurrencyConversionException(from, to, String.format("Currency %1$s not supported", from));
    1.69 +		if (toRate == null)
    1.70 +			throw new CurrencyConversionException(from, to, String.format("Currency %1$s not supported", to));
    1.71 +
    1.72 +		return (value / fromRate) * toRate;
    1.73 +	}
    1.74 +}