Java枚举类型Enum的用法

package com.rensanning.enumtest; import java.util.EnumMap; import java.util.EnumSet; import java.util.Map; import java.util.Set; import com.rensanning.enumtest.EnumBean.ConstructableEnums; import com.rensanning.enumtest.EnumBean.EnumWithInterface; import com.rensanning.enumtest.EnumBean.EnumsWithMethod; import com.rensanning.enumtest.EnumBean.NumericEnums; public class Main { public static void main(String[] args) { testEnumBasics(); testEnumCollection(); testEnumConversions(); } private static void testEnumBasics() { // ---------------------------------------- System.out.println("printing NumericEnums.values():"); for (NumericEnums e : NumericEnums.values()) { System.out.print(e.toString() + "\t"); }//ONE TWO THREE FOUR FIVE System.out.println(); NumericEnums o = NumericEnums.ONE; if(o == NumericEnums.ONE){ System.out.println("enum in java can be compared using =="); } System.out.println(NumericEnums.valueOf("ONE").equals(NumericEnums.ONE));//true try { NumericEnums.valueOf("one"); } catch (IllegalArgumentException e) { System.out.println("one is not exist!"); } NumericEnums one = NumericEnums.ONE; switch(one) { case ONE: System.out.println("ONE"); break; } // ---------------------------------------- System.out.println("printing ConstructableEnums.values():"); for (ConstructableEnums e : ConstructableEnums.values()) { System.out.print(e.toString() + "\t"); }//ABC DEF GHI JKL System.out.println(); System.out.println(ConstructableEnums.valueOf("DEF").equals(ConstructableEnums.DEF));//true System.out.println(ConstructableEnums.DEF.getContent());//num=[20], name=[def] // ---------------------------------------- System.out.println(EnumsWithMethod.MORNING.hello("foo")); //Good Morning, foo. zzz... System.out.println(EnumsWithMethod.AFTERNOON.hello("bar"));//Good Afternoon, bar. tea or coffee ? System.out.println(EnumsWithMethod.EVENING.hello("baz"));//Good Evening, baz. sleep, sleep. System.out.println(EnumsWithMethod.MORNING.getGreeting());//Good Morning System.out.println(EnumsWithMethod.AFTERNOON.getGreeting());//Good Afternoon, but sleepy... System.out.println(EnumsWithMethod.EVENING.getGreeting());//Good Evening // ---------------------------------------- System.out.println(EnumWithInterface.ME_THEN_YOU.sayHello("abc"));//I'm foo, you're abc. System.out.println(EnumWithInterface.YOU_THEN_ME.sayHello("def"));//You're def, I'm bar. } private static void testEnumCollection() { // EnumMap---------------------------------------- Map<NumericEnums, String> numerics = new EnumMap<NumericEnums, String>(NumericEnums.class); numerics.put(NumericEnums.ONE, "one"); numerics.put(NumericEnums.TWO, "two"); numerics.put(NumericEnums.THREE, "three"); numerics.put(NumericEnums.FOUR, "four"); numerics.put(NumericEnums.FIVE, "five"); System.out.println(numerics.get(NumericEnums.FOUR));//four // EnumSet---------------------------------------- Set<NumericEnums> s1 = EnumSet.of(NumericEnums.TWO, NumericEnums.THREE); System.out.println(s1.contains(NumericEnums.TWO));//true System.out.println(s1.contains(NumericEnums.FOUR));//false Set<NumericEnums> s2 = EnumSet.noneOf(NumericEnums.class); System.out.println(s2.size());//0 Set<NumericEnums> s3 = EnumSet.range(NumericEnums.TWO, NumericEnums.FOUR); System.out.println(s3.contains(NumericEnums.ONE));//false System.out.println(s3.contains(NumericEnums.TWO));//true System.out.println(s3.contains(NumericEnums.THREE));//true System.out.println(s3.contains(NumericEnums.FOUR));//true System.out.println(s3.contains(NumericEnums.FIVE));//false } private static void testEnumConversions() { // int->Enum System.out.println(NumericEnums.values()[0].equals(NumericEnums.ONE));//true // String->Enum System.out.println(NumericEnums.valueOf("ONE").equals(NumericEnums.ONE));//true // Enum->int---------------------------------------- System.out.println(NumericEnums.ONE.ordinal());//0 System.out.println(NumericEnums.TWO.ordinal());//1 System.out.println(NumericEnums.THREE.ordinal());//2 System.out.println(NumericEnums.FOUR.ordinal());//3 System.out.println(NumericEnums.FIVE.ordinal());//4 // Enum->String---------------------------------------- System.out.println(NumericEnums.ONE.name());//ONE System.out.println(NumericEnums.TWO.name());//TWO System.out.println(NumericEnums.THREE.name());//THREE System.out.println(NumericEnums.FOUR.name());//FOUR System.out.println(NumericEnums.FIVE.name());//FIVE System.out.println(NumericEnums.ONE.toString());//ONE System.out.println(NumericEnums.TWO.toString());//TWO System.out.println(NumericEnums.THREE.toString());//THREE System.out.println(NumericEnums.FOUR.toString());//FOUR System.out.println(NumericEnums.FIVE.toString());//FIVE } }