+ * Feel free to create additional classes or rename this one, just keep all
+ * the API and its implementation in this package. Do not spread it outside
+ * to other packages.
+ */
+public final class Convertor {
+ private String currency1;
+ private String currency2;
+ private Rate rate;
+
+ Convertor(String currency1, String currency2, Rate rate) {
+ if ((currency1 == null)||(currency2 == null)||(rate == null)) {
+ throw new IllegalArgumentException("All arguments have to be non-null.");
+ }
+ this.currency1 = currency1;
+ this.currency2 = currency2;
+ this.rate = rate;
+ }
+
+ public double convert(String fromCurrency, String toCurrency, int amount) {
+ if ((fromCurrency == null)||(toCurrency == null)) {
+ throw new IllegalArgumentException("All arguments have to be non-null.");
+ }
+
+ if (currency1.equals(fromCurrency) && currency2.equals(toCurrency)) {
+ return rate.convertAtoB(amount);
+ } else if (currency2.equals(fromCurrency) && currency1.equals(toCurrency)) {
+ return rate.convertBtoA(amount);
+ } else {
+ throw new IllegalArgumentException("Convertor " + this.toString() +
+ " cannot work with currencies " + fromCurrency + " and " + toCurrency + ".");
+ }
+ }
+
+ public double convert(String fromCurrency, String toCurrency, double amount) {
+ if ((fromCurrency == null)||(toCurrency == null)) {
+ throw new IllegalArgumentException("All arguments have to be non-null.");
+ }
+
+ if (currency1.equals(fromCurrency) && currency2.equals(toCurrency)) {
+ return rate.convertAtoB(amount);
+ } else if (currency2.equals(fromCurrency) && currency1.equals(toCurrency)) {
+ return rate.convertBtoA(amount);
+ } else {
+ throw new IllegalArgumentException("Convertor " + this.toString() +
+ " cannot work with currencies " + fromCurrency + " and " + toCurrency + ".");
+ }
+ }
+
+ @Override
+ public String toString() {
+ return currency1+currency2;
+ }
+
+ @Override
+ public boolean equals(Object obj) {
+ if (obj == null) {
+ return false;
+ }
+ if (getClass() != obj.getClass()) {
+ return false;
+ }
+ final Convertor other = (Convertor) obj;
+ if (this.currency1 != other.currency1 && (this.currency1 == null || !this.currency1.equals(other.currency1))) {
+ return false;
+ }
+ if (this.currency2 != other.currency2 && (this.currency2 == null || !this.currency2.equals(other.currency2))) {
+ return false;
+ }
+ if (this.rate != other.rate && (this.rate == null || !this.rate.equals(other.rate))) {
+ return false;
+ }
+ return true;
+ }
+
+ @Override
+ public int hashCode() {
+ int hash = 5;
+ hash = 67 * hash + (this.currency1 != null ? this.currency1.hashCode() : 0);
+ hash = 67 * hash + (this.currency2 != null ? this.currency2.hashCode() : 0);
+ hash = 67 * hash + (this.rate != null ? this.rate.hashCode() : 0);
+ return hash;
+ }
+}
diff -r b4c6b18eaf3f -r a022dd2a5d30 task1/solution14/src/org/apidesign/apifest08/currency/ConvertorFactory.java
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/task1/solution14/src/org/apidesign/apifest08/currency/ConvertorFactory.java Tue Sep 30 13:51:18 2008 +0200
@@ -0,0 +1,28 @@
+
+package org.apidesign.apifest08.currency;
+
+public final class ConvertorFactory {
+
+ //Singleton
+ private static ConvertorFactory thisFactory = new ConvertorFactory();
+ private ConvertorFactory() {};
+ public static ConvertorFactory newInstance() {
+ return thisFactory;
+ }
+
+ public Convertor createConvertor(String currency1, String currency2, Rate rate) {
+ return new Convertor(currency1, currency2, rate);
+ }
+
+ public Convertor createConvertor(String currency1, String currency2, int amount1, int amount2) {
+ return new Convertor(currency1, currency2, new Rate(amount1, amount2));
+ }
+
+ public Convertor createConvertor(String currency1, String currency2, double amount1, double amount2) {
+ return new Convertor(currency1, currency2, new Rate(amount1, amount2));
+ }
+
+ public Convertor createConvertor(String currency1, String currency2, double rate) {
+ return new Convertor(currency1, currency2, new Rate(rate));
+ }
+}
diff -r b4c6b18eaf3f -r a022dd2a5d30 task1/solution14/src/org/apidesign/apifest08/currency/Rate.java
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/task1/solution14/src/org/apidesign/apifest08/currency/Rate.java Tue Sep 30 13:51:18 2008 +0200
@@ -0,0 +1,68 @@
+
+package org.apidesign.apifest08.currency;
+
+public final class Rate {
+
+ private double rate;
+
+ public Rate(int amountA, int amountB) {
+ rate = amountA / (double)amountB;
+ if (rate <= 0) {
+ throw new IllegalArgumentException("Exchange rate must be positive.");
+ }
+ }
+
+ public Rate(double amountA, double amountB) {
+ rate = amountA / amountB;
+ if (rate <= 0) {
+ throw new IllegalArgumentException("Exchange rate must be positive.");
+ }
+ }
+
+ public Rate(double rate) {
+ this.rate = rate;
+ if (this.rate <= 0) {
+ throw new IllegalArgumentException("Exchange rate must be positive.");
+ }
+ }
+
+ public double convertAtoB(int a) {
+ return a / rate;
+ }
+
+ public double convertAtoB(double a) {
+ return a / rate;
+ }
+
+ public double convertBtoA(int b) {
+ return b * rate;
+ }
+
+ public double convertBtoA(double b) {
+ return b * rate;
+ }
+
+
+ @Override
+ public boolean equals(Object obj) {
+ if (obj == null) {
+ return false;
+ }
+ if (getClass() != obj.getClass()) {
+ return false;
+ }
+ final Rate other = (Rate) obj;
+ return true;
+ }
+
+ @Override
+ public int hashCode() {
+ int hash = 5;
+ return hash;
+ }
+
+ @Override
+ public String toString() {
+ return ""+rate;
+ }
+}
diff -r b4c6b18eaf3f -r a022dd2a5d30 task1/solution14/test/org/apidesign/apifest08/test/Task1Test.java
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/task1/solution14/test/org/apidesign/apifest08/test/Task1Test.java Tue Sep 30 13:51:18 2008 +0200
@@ -0,0 +1,144 @@
+package org.apidesign.apifest08.test;
+
+import junit.framework.TestCase;
+import org.apidesign.apifest08.currency.Convertor;
+import org.apidesign.apifest08.currency.ConvertorFactory;
+
+/** Finish the Convertor API, and then write bodies of methods inside
+ * of this class to match the given tasks. To fullfil your task, use the
+ * API define in the org.apidesign.apifest08.currency package.
+ * Do not you reflection, or other hacks as your code
+ * shall run without any runtime permissions.
+ */
+public class Task1Test extends TestCase {
+ public Task1Test(String testName) {
+ super(testName);
+ }
+
+ @Override
+ protected void setUp() throws Exception {
+ }
+
+ @Override
+ protected void tearDown() throws Exception {
+ }
+
+ //
+ // Imagine that there are three parts of the whole system:
+ // 1. there is someone who knows the current exchange rate
+ // 2. there is someone who wants to do the conversion
+ // 3. there is the API between 1. and 2. which allows them to communicate
+ // Please design such API
+ //
+
+ /** Create convertor that understands two currencies, CZK and
+ * USD. Make 1 USD == 17 CZK. This is a method provided for #1 group -
+ * e.g. those that know the exchange rate. They somehow need to create
+ * the objects from the API and tell them the exchange rate. The API itself
+ * knows nothing about any rates, before the createCZKtoUSD method is called.
+ *
+ * Creation of the convertor shall not require subclassing of any class
+ * or interface on the client side.
+ *
+ * @return prepared convertor ready for converting USD to CZK and CZK to USD
+ */
+ public static Convertor createCZKtoUSD() {
+ return ConvertorFactory.newInstance().createConvertor("CZK", "USD", 17, 1);
+ }
+
+ /** Create convertor that understands two currencies, CZK and
+ * SKK. Make 100 SKK == 80 CZK. Again this is method for the #1 group -
+ * it knows the exchange rate, and needs to use the API to create objects
+ * with the exchange rate. Anyone shall be ready to call this method without
+ * any other method being called previously. The API itself shall know
+ * nothing about any rates, before this method is called.
+ *
+ * Creation of the convertor shall not require subclassing of any class
+ * or interface on the client side.
+ *
+ * @return prepared convertor ready for converting SKK to CZK and CZK to SKK
+ */
+ public static Convertor createSKKtoCZK() {
+ return ConvertorFactory.newInstance().createConvertor("SKK", "CZK", 100, 80);
+ }
+
+ //
+ // now the methods for group #2 follow:
+ // this group knows nothing about exchange rates, but knows how to use
+ // the API to do conversions. It somehow (by calling one of the factory
+ // methods) gets objects from the API and uses them to do the conversions.
+ //
+
+ /** Use the convertor from createCZKtoUSD method and do few conversions
+ * with it.
+ */
+ public void testCurrencyCZKUSD() throws Exception {
+ Convertor c = createCZKtoUSD();
+ // convert $5 to CZK using c:
+ assertEquals("Result is 85 CZK", 85.0, c.convert("USD", "CZK", 5));
+
+ // convert $8 to CZK
+ assertEquals("Result is 136 CZK", 136.0, c.convert("USD", "CZK", 8));
+
+ // convert 1003CZK to USD
+ assertEquals("Result is 59 CZK", 59.0, c.convert("CZK", "USD", 1003));
+ }
+
+ /** Use the convertor from createSKKtoCZK method and do few conversions
+ * with it.
+ */
+ public void testCurrencySKKCZK() throws Exception {
+ Convertor c = createSKKtoCZK();
+ // convert 16CZK using c:
+ // assertEquals("Result is 20 SKK");
+ assertEquals("Result is 20 SKK", 20.0, c.convert("CZK", "SKK", 16));
+
+ // convert 500SKK to CZK
+ // assertEquals("Result is 400 CZK");
+ assertEquals("Result is 400 SKK", 400.0, c.convert("SKK", "CZK", 500));
+ }
+
+ /** Verify that the CZK to USD convertor knows nothing about SKK.
+ */
+ public void testCannotConvertToSKKwithCZKUSDConvertor() throws Exception {
+ Convertor c = createCZKtoUSD();
+ // convert $5 to SKK, the API shall say this is not possible
+ try {
+ c.convert("USD", "SKK", 5);
+ fail("Converting SKK with CZKUSD convertor is impossible");
+ } catch (IllegalArgumentException e){
+ //ok
+ }
+
+ // convert 500 SKK to CZK, the API shall say this is not possible
+ try {
+ c.convert("SKK", "CZK", 500);
+ fail("Converting SKK with CZKUSD convertor is impossible");
+ } catch (IllegalArgumentException e){
+ //ok
+ }
+
+ }
+
+ /** Verify that the CZK to SKK convertor knows nothing about USD.
+ */
+ public void testCannotConvertToUSDwithCZKSKKConvertor() throws Exception {
+ Convertor c = createSKKtoCZK();
+ // convert $5 to SKK, the API shall say this is not possible
+ try {
+ c.convert("USD", "SKK", 5);
+ fail("Converting SKK with SKKCZK convertor is impossible");
+ } catch (IllegalArgumentException e){
+ //ok
+ }
+
+ // convert 500 CZK to USD, the API shall say this is not possible
+ try {
+ c.convert("CZK", "USD", 500);
+ fail("Converting USD with SKKCZK convertor is impossible");
+ } catch (IllegalArgumentException e){
+ //ok
+ }
+
+ }
+}