java --- 枚举类

目录

一、枚举类

二、创建枚举类

2.1、JDK5.0之前创建 

 2.2、JDK5.0使用enum创建

 三、枚举类常用方法

 四、枚举类实现接口

一、枚举类

枚举类型本质上也是一种类，只不过是这个类的对象是有限的、固定的几个，不能让用户随意创建。

二、创建枚举类

2.1、JDK5.0之前创建 

public class SeasonTest {public static void main(String[] args) {System.out.println(Season.SPRING.getSeasonName());}
}
//JDK5.0之前创建方式
class Season{//定义属性private final String seasonName;private final String seasonDesc;//构造器私有化private Season(String seasonName, String seasonDesc) {this.seasonName = seasonName;this.seasonDesc = seasonDesc;}//提高get方法public String getSeasonName() {return seasonName;}public String getSeasonDesc() {return seasonDesc;}//创建当前类的实例public static final Season SPRING  = new Season("春天","春暖花开");public static final Season SUMMER  = new Season("夏天","夏日炎炎");public static final Season AUTUMN  = new Season("秋天","秋高气爽");public static final Season WINTER  = new Season("冬天","白雪皑皑");@Overridepublic String toString() {return "Season{" +"seasonName='" + seasonName + '\'' +", seasonDesc='" + seasonDesc + '\'' +'}';}
}

 2.2、JDK5.0使用enum创建

public class SeasonTest1 {public static void main(String[] args) {System.out.println(Season1.SPRING.getSeasonName());}
}
//JDK5.0创建方式
enum Season1{//创建当前类的实例SPRING("春天","春暖花开"),SUMMER("夏天","夏日炎炎"),AUTUMN("秋天","秋高气爽"),WINTER("冬天","白雪皑皑");//定义属性private final String seasonName;private final String seasonDesc;//构造器私有化private Season1(String seasonName, String seasonDesc) {this.seasonName = seasonName;this.seasonDesc = seasonDesc;}//提高get方法public String getSeasonName() {return seasonName;}public String getSeasonDesc() {return seasonDesc;}
}

 三、枚举类常用方法

String toString(): 默认返回的是常量名（对象名），可以继续手动重写该方法！
   
static 枚举类型[] values():返回枚举类型的对象数组。该方法可以很方便地遍历所有的枚举值，是一个静态方法
   
static 枚举类型 valueOf(String name)：可以把一个字符串转为对应的枚举类对象。要求字符串必须是枚举类对象的“名字”。如不是，会有运行时异常：IllegalArgumentException。
   
String name():得到当前枚举常量的名称。建议优先使用toString()。
   
int ordinal():返回当前枚举常量的次序号，默认从0开始

 //toString()System.out.println(Season1.SPRING);//name()System.out.println(Season1.SPRING.name());//values()Season1[] values = Season1.values();for (Season1 season1:values) {System.out.println(season1);}//valueOf():可以把一个字符串转为对应的枚举类对象。要求字符串必须是枚举类对象的“名字”。// 如不是，会有运行时异常：IllegalArgumentException。System.out.println(Season1.valueOf("SPRING"));//ordinal()System.out.println(Season1.SUMMER.ordinal());

 四、枚举类实现接口

4.1、枚举的对象调用执行同一个方法

public class SeasonTest2 {public static void main(String[] args) {Season2.SPRING.method();}
}
interface Test01{public void method();
}
//JDK5.0创建方式
enum Season2 implements Test01{//创建当前类的实例SPRING("春天","春暖花开"),SUMMER("夏天","夏日炎炎"),AUTUMN("秋天","秋高气爽"),WINTER("冬天","白雪皑皑");@Overridepublic void method() {System.out.println("实现接口成功");}//定义属性private final String seasonName;private final String seasonDesc;//构造器私有化private Season2(String seasonName, String seasonDesc) {this.seasonName = seasonName;this.seasonDesc = seasonDesc;}
}

4.2、枚举类的每个对象重写接口中的方法，执行每个对象重写的方法

public class SeasonTest2 {public static void main(String[] args) {Season2[] values = Season2.values();for (int i = 0; i < values.length; i++) {values[i].method();}}
}
interface Test01{public void method();
}
//JDK5.0创建方式
enum Season2 implements Test01{//创建当前类的实例SPRING("春天","春暖花开"){@Overridepublic void method() {System.out.println("春天重写接口方法");}},SUMMER("夏天","夏日炎炎"){@Overridepublic void method() {System.out.println("夏天重写接口方法");}},AUTUMN("秋天","秋高气爽"){@Overridepublic void method() {System.out.println("秋天重写接口方法");}},WINTER("冬天","白雪皑皑"){@Overridepublic void method() {System.out.println("冬天重写接口方法");}};
//    @Override
//    public void method() {
//        System.out.println("实现接口成功");
//    }//定义属性private final String seasonName;private final String seasonDesc;//构造器私有化private Season2(String seasonName, String seasonDesc) {this.seasonName = seasonName;this.seasonDesc = seasonDesc;}
}