1、用法一：常量
在JDK1.5之前，我们定义常量都是：publicstaticfianl....。现在好了，有了枚举，可以把相关的常量分组到一个枚举类型里，而且枚举提供了比常量更多的方法。
Java代码
public enum Color { RED, GREEN, BLANK, YELLOW }
2、用法二：switch
JDK1.6之前的switch语句只支持int,char,enum类型，使用枚举，能让我们的代码可读性更强。
Java代码
enum Signal { GREEN, YELLOW, RED } public class TrafficLight { Signal color = Signal.RED; public void change() { switch (color) { case RED: color = Signal.GREEN; break; case YELLOW: color = Signal.RED; break; case GREEN: color = Signal.YELLOW; break; } } }
3、用法三：向枚举中添加新方法
如果打算自定义自己的方法，那么必须在enum实例序列的最后添加一个分号。而且Java要求必须先定义enum实例。
public enum Color { RED("红色", 1), GREEN("绿色", 2), BLANK("白色", 3), YELLO("黄色", 4); // 成员变量 private String name; private int index; // 构造方法 private Color(String name, int index) { this.name = name; this.index = index; } // 普通方法 public static String getName(int index) { for (Color c : Color.values()) { if (c.getIndex() == index) { return c.name; } } return null; } // get set 方法 public String getName() { return name; } public void setName(String name) { this.name = name; } public int getIndex() { return index; } public void setIndex(int index) { this.index = index; } }
4、用法四：覆盖枚举的方法
下面给出一个toString()方法覆盖的例子。
public enum Color { RED("红色"), GREEN("绿色"), BLANK("白色"), YELLO("黄色"); // 成员变量 private String name; // 构造方法 private Color(String name) { this.name = name; } // 覆盖方法 @Override public String toString() { return this.name; } }
5、用法五：实现接口
所有的枚举都继承自java.lang.Enum类。由于Java不支持多继承，所以枚举对象不能再继承其他类。
Java代码
public interface Behaviour { void print(); String getInfo(); } public enum Color implements Behaviour{ RED("红色", 1), GREEN("绿色", 2), BLANK("白色", 3), YELLO("黄色", 4); // 成员变量 private String name; private int index; // 构造方法 private Color(String name, int index) { this.name = name; this.index = index; } //接口方法 @Override public String getInfo() { return this.name; } //接口方法 @Override public void print() { System.out.println(this.index+":"+this.name); } }
6、用法六：使用接口组织枚举
Java代码
public interface Food { enum Coffee implements Food{ BLACK_COFFEE,DECAF_COFFEE,LATTE,CAPPUCCINO } enum Dessert implements Food{ FRUIT, CAKE, GELATO } }
7、用法七：关于枚举集合的使用
java.util.EnumSet和java.util.EnumMap是两个枚举集合。EnumSet保证集合中的元素不重复；EnumMap中的key是enum类型，而value则可以是任意类型。
8、实践
package com.ylink.cms.pojo.lucene; import java.util.Date; public class LuceneContent { private String id; private String channelId; private String title; public enum LuceneContentType { article, channel } private LuceneContentType type; private String remark; private String content; private Date createDate; private String author; public String getId() { return id; } public void setId(String id) { this.id = id; } public String getChannelId() { return channelId; } public void setChannelId(String channelId) { this.channelId = channelId; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } public String getContent() { return content; } public void setContent(String content) { this.content = content; } public String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public LuceneContentType getType() { return type; } public void setType(LuceneContentType type) { this.type = type; } public Date getCreateDate() { return createDate; } public void setCreateDate(Date createDate) { this.createDate = createDate; } public String getRemark() { return remark; } public void setRemark(String remark) { this.remark = remark; } @Override public String toString() { return "LuceneContent [id=" + id + ", channelId=" + channelId + ", title=" + title + ", type=" + type + ", remark=" + remark + ", content=" + content + ", createDate=" + createDate + ", author=" + author + "]"; } }
package com.ylink.cms.util; import java.util.ArrayList; import java.util.List; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.ylink.cms.pojo.channel.Channel; import com.ylink.cms.pojo.content.Content; import com.ylink.cms.pojo.lucene.LuceneContent; import com.ylink.cms.pojo.lucene.LuceneContent.LuceneContentType; public class LuceneContentTransUtil { private static final Logger logger = LoggerFactory.getLogger(LuceneContentTransUtil.class); /**将栏目转化可索引内容*/ public static LuceneContent parseContent(Content content){ LuceneContent luceneContent = new LuceneContent(); luceneContent.setAuthor(content.getAuthor()); luceneContent.setChannelId(String.valueOf(content.getChannelId())); luceneContent.setContent(content.getContentDetail()); luceneContent.setCreateDate(content.getCrtdate()); luceneContent.setId(String.valueOf(content.getContentId())); luceneContent.setRemark(content.getRemark()); luceneContent.setTitle(content.getContentTitle()); luceneContent.setType(LuceneContentType.article); return luceneContent; } /**内容可索引化*/ public static LuceneContent praseChannel(Channel channel){ LuceneContent luceneContent = new LuceneContent(); luceneContent.setAuthor(""); luceneContent.setChannelId(String.valueOf(channel.getChannelId())); luceneContent.setContent(channel.getChannelIntro()); luceneContent.setCreateDate(channel.getCrtdate()); luceneContent.setId(String.valueOf(channel.getChannelId())); luceneContent.setRemark(channel.getChannelIntro()); luceneContent.setTitle(channel.getChannelName()); luceneContent.setType(LuceneContentType.channel); return luceneContent; } public static List<LuceneContent> praseChannelsOrContents(List<Channel> channels, List<Content> contents){ List<LuceneContent> luceneContents = new ArrayList<LuceneContent>(); /**将栏目转化可索引内容*/ if(null != channels && channels.size()>=1){ for(int i =0; i< channels.size(); i++){ LuceneContent lc = praseChannel(channels.get(i)); luceneContents.add(lc); } } /**内容可索引化*/ if(null != contents && contents.size()>=1){ for(int i =0; i< contents.size(); i++){ LuceneContent lc = parseContent(contents.get(i)); luceneContents.add(lc); } } logger.info("luceneContents.size(): "+luceneContents.size()); return luceneContents; } }