枚举的一些用法

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枚举策略模式：

package com.price.effective.enum1;public enum Pay {MONDAY(PayType.WEEKDAY),SUNDAY(PayType.WEEKEND);private PayType payType;Pay(PayType payType){this.payType = payType;}double pay(double hoursworked, double payRate){return payType.overPay(hoursworked - 8, payRate) + payRate*8;}private enum PayType{WEEKEND{@Overridedouble overPay(double hours, double payRate) {return hours * payRate * 3;}},WEEKDAY{@Overridedouble overPay(double hours, double payRate) {return hours * payRate;}};abstract double overPay(double hours, double payRate);}}

枚举值域

package com.price.effective.enum1;import java.util.EnumSet;import java.util.Set;public class TestEnumSet {// 一般的结合是List或者Set, 还有种跟好的办法如下：public static final int STYLE_BOLD = 1 << 0;public static final int STYLE_ITALIC = 1 << 1;// 这样就能够使用位运算来得到一个int型表示的集合，效率较高public void applyStyles(int styles){if((styles & STYLE_BOLD) != 0){System.out.println("BOLD");}if((styles & STYLE_ITALIC) != 0){System.out.println("ITALIC");}}// 下面用EnumSet来实现以下public enum Style{BOLD, ITALIC};public void applyStyles(Set<Style> styles){if(styles.contains(Style.BOLD)){System.out.println("BOLD");}if(styles.contains(Style.ITALIC)){System.out.println("ITALIC");}}public static void main(String[] args) {TestEnumSet tes = new TestEnumSet();tes.applyStyles(TestEnumSet.STYLE_BOLD | TestEnumSet.STYLE_ITALIC);tes.applyStyles(EnumSet.of(Style.BOLD, Style.ITALIC));}}

枚举作为Map的key:

package com.price.effective.enum1;import java.util.ArrayList;import java.util.Collection;import java.util.EnumMap;import java.util.List;import java.util.Map;/** * 给动物分类 * * @author cdwangzijian * */public class TestEnumMap {public static void main(String[] args) {// 一种方式是便利所有的动物，根据类型加入到对应的集合中// 稍微好一点的可能可以利用类型名称数组来分类，如下：List<Animal>[] animalByType = new List[Animal.Type.values().length];for (int i = 0 ; i < animalByType.length; i++) {animalByType[i] = new ArrayList<Animal>();}for (Animal a : Animal.getAnimals()) {animalByType[a.getType().ordinal()].add(a);}printResult(animalByType);Map<Animal.Type, Animal> animalTypeMap = new EnumMap<Animal.Type, Animal>(Animal.Type.class);for (Animal a : Animal.getAnimals()) {animalTypeMap.put(a.getType(), a);}printResult(animalTypeMap.values());}private static void printResult(Collection<Animal> values) {System.out.println(values);}private static void printResult(List<Animal>[] animalByType) {for (List<Animal> as : animalByType) {System.out.println(as);}}}class Animal{public static enum Type{LINGZHANG, CAT, FLY};private String name;private Type type;public Animal(String name, Type type) {this.name = name;this.type = type;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Type getType() {return type;}public void setType(Type type) {this.type = type;}@Overridepublic String toString() {return "name:" + name;}public static List<Animal> getAnimals(){Animal tiger = new Animal("tiger", Animal.Type.CAT);Animal chiken = new Animal("chiken", Animal.Type.LINGZHANG);Animal monkey = new Animal("monkey", Animal.Type.FLY);List<Animal> animals = new ArrayList<Animal>();animals.add(tiger);animals.add(chiken);animals.add(monkey);return animals;}}

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