枚举的一些用法-白红宇

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{			@Override			double overPay(double hours, double payRate) {				return hours * payRate * 3;			}		},				WEEKDAY{			@Override			double 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

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
    
     [] animalByType = new List[Animal.Type.values().length];		for (int i = 0 ; i < animalByType.length; i++) {			animalByType[i] = new ArrayList
     
      ();		}		for (Animal a : Animal.getAnimals()) {			animalByType[a.getType().ordinal()].add(a);		}				printResult(animalByType);						Map
      
        animalTypeMap = new EnumMap
       
        (Animal.Type.class);		for (Animal a : Animal.getAnimals()) {			animalTypeMap.put(a.getType(), a);		}				printResult(animalTypeMap.values());	}	private static void printResult(Collection
        
          values) {		System.out.println(values);	}	private static void printResult(List
         
          [] animalByType) { for (List
          
            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; } @Override public String toString() { return "name:" + name; } public static List
           
             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
            
              animals = new ArrayList
             
              (); animals.add(tiger); animals.add(chiken); animals.add(monkey); return animals; }}