- * In this example {@link Nazgul} is the Multiton and we can ask single {@link Nazgul} from it using - * {@link NazgulName}. The {@link Nazgul}s are statically initialized and stored in concurrent hash - * map. + * There is more than one way to implement the multiton design pattern. In the first example + * {@link Nazgul} is the Multiton and we can ask single {@link Nazgul} from it using {@link NazgulName}. + * The {@link Nazgul}s are statically initialized and stored in concurrent hash map. + *
+ * In the enum implementation {@link NazgulEnum} is the multiton. It is static and mutable because + * of the way java supports enums. * */ public class App { @@ -46,6 +49,7 @@ public class App { * @param args command line args */ public static void main(String[] args) { + // eagerly initialized multiton LOGGER.info("KHAMUL={}", Nazgul.getInstance(NazgulName.KHAMUL)); LOGGER.info("MURAZOR={}", Nazgul.getInstance(NazgulName.MURAZOR)); LOGGER.info("DWAR={}", Nazgul.getInstance(NazgulName.DWAR)); @@ -55,5 +59,16 @@ public class App { LOGGER.info("ADUNAPHEL={}", Nazgul.getInstance(NazgulName.ADUNAPHEL)); LOGGER.info("REN={}", Nazgul.getInstance(NazgulName.REN)); LOGGER.info("UVATHA={}", Nazgul.getInstance(NazgulName.UVATHA)); + + // enum multiton + LOGGER.info("KHAMUL={}", NazgulEnum.KHAMUL); + LOGGER.info("MURAZOR={}", NazgulEnum.MURAZOR); + LOGGER.info("DWAR={}", NazgulEnum.DWAR); + LOGGER.info("JI_INDUR={}", NazgulEnum.JI_INDUR); + LOGGER.info("AKHORAHIL={}", NazgulEnum.AKHORAHIL); + LOGGER.info("HOARMURATH={}", NazgulEnum.HOARMURATH); + LOGGER.info("ADUNAPHEL={}", NazgulEnum.ADUNAPHEL); + LOGGER.info("REN={}", NazgulEnum.REN); + LOGGER.info("UVATHA={}", NazgulEnum.UVATHA); } } diff --git a/multiton/src/main/java/com/iluwatar/multiton/NazgulEnum.java b/multiton/src/main/java/com/iluwatar/multiton/NazgulEnum.java new file mode 100644 index 000000000..375176c4f --- /dev/null +++ b/multiton/src/main/java/com/iluwatar/multiton/NazgulEnum.java @@ -0,0 +1,33 @@ +/** + * The MIT License + * Copyright (c) 2014-2016 Ilkka Seppälä + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +package com.iluwatar.multiton; + +/** + * enum based multiton implementation + * + */ +public enum NazgulEnum { + + KHAMUL, MURAZOR, DWAR, JI_INDUR, AKHORAHIL, HOARMURATH, ADUNAPHEL, REN, UVATHA; + +} diff --git a/multiton/src/test/java/com/iluwatar/multiton/NazgulEnumTest.java b/multiton/src/test/java/com/iluwatar/multiton/NazgulEnumTest.java new file mode 100644 index 000000000..b718b9c68 --- /dev/null +++ b/multiton/src/test/java/com/iluwatar/multiton/NazgulEnumTest.java @@ -0,0 +1,50 @@ +/** + * The MIT License + * Copyright (c) 2014-2016 Ilkka Seppälä + * + * Permission is hereby granted, free of charge, to any person obtaining a copy + * of this software and associated documentation files (the "Software"), to deal + * in the Software without restriction, including without limitation the rights + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell + * copies of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included in + * all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN + * THE SOFTWARE. + */ +package com.iluwatar.multiton; + +import static org.junit.jupiter.api.Assertions.*; + +import org.junit.jupiter.api.Test; + +/** + * @author anthony + * + */ +class NazgulEnumTest { + + /** + * Check that multiple calls to any one of the instances in the multiton returns + * only that one particular instance, and do that for all instances in multiton + */ + @Test + public void testTheSameObjectIsReturnedWithMultipleCalls() { + for (int i = 0; i < NazgulEnum.values().length; i++) { + NazgulEnum instance1 = NazgulEnum.values()[i]; + NazgulEnum instance2 = NazgulEnum.values()[i]; + NazgulEnum instance3 = NazgulEnum.values()[i]; + assertSame(instance1, instance2); + assertSame(instance1, instance3); + assertSame(instance2, instance3); + } + } +}