Created
January 10, 2014 07:13
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Enum lookup Map
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| // Först behöver vi ett interface | |
| package net.valfridsson; | |
| public interface IdentityEnum<I, E extends Enum<E>> { | |
| /** | |
| * @return Hämtar ut {@link I} för {@link E} | |
| */ | |
| I getId(); | |
| } | |
| // Sedan behövver vi mekanismen som hanterar uppslagen mellan enumarna | |
| package net.valfridsson; | |
| import java.util.HashMap; | |
| import java.util.Map; | |
| import java.util.Set; | |
| public class EnumLookupMap<I, E extends Enum<E> & IdentityEnum<I, E>> { | |
| private Map<I, E> map = new HashMap<I, E>(); | |
| public EnumLookupMap(Class<E> clazz) { | |
| for (E e : clazz.getEnumConstants()) { | |
| map.put(e.getId(), e); | |
| } | |
| } | |
| public E get(I key) { | |
| return map.get(key); | |
| } | |
| public Set<Map.Entry<I, E>> getEntries() { | |
| return map.entrySet(); | |
| } | |
| } | |
| // Hur använder vi den: | |
| private enum EnumB { | |
| VALUE_1, VALUE_2; | |
| } | |
| private enum EnumA implements IdentityEnum<EnumB, EnumA> { | |
| VALUE_1(EnumB.VALUE_1),VALUE_2(EnumB.VALUE_2); | |
| private EnumB enumb; | |
| public static EnumLookupMap<EnumB, EnumA> map = new EnumLookupMap<EnumB, EnumA>(EnumA.class); | |
| private EnumA(EnumB enumb) { | |
| this.enumb = enumb; | |
| } | |
| public static EnumA valueOf(EnumB enumB){ | |
| return map.get(enumB); | |
| } | |
| public EnumB getId() { | |
| return enumb; | |
| } | |
| } | |
| // Man kan nu hämta ut EnumB från EnumA - getId() | |
| // samt få ut EnumA utifrån EnumB - valueOf(EnumB enum) | |
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