JDK 1.5 新增enum定义枚举类
1. 如何使用关键字enum定义枚举类（JDK 1.5 新增）
说明：定义的枚举类默认继承于java.lang.Enum类
public enum SeasonEnum
{
//1.提供当前枚举类的对象，多个对象之间用","隔开，末尾对象";"结束
SPRING("春天","春风又绿江南岸"),
SUMMER("夏天","映日荷花别样红"),
AUTUMN("秋天","秋水共长天一色"),
WINTER("冬天","窗含西岭千秋雪");
//2. 对象如果有实例变量，应该声明为private final，并在构造器中初始化
private final String seasonName;
private final String seasonDesc;
//3. 私有化类的构造器，保证不能在类的外部创建其对象(否则对象个数不确定）
private SeasonEnum(String seasonName, String seasonDesc)
{
this.seasonName = seasonName;
this.seasonDesc = seasonDesc;
}
}
2. Enum类的主要方法
-
values()方法：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。
-
valueOf(String str)：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。
-
toString()：返回当前枚举类对象常量的名称。
public class SeasonTest1 {
public static void main(String[] args) {
Season1 summer = Season1.SUMMER;
//toString():返回枚举类对象的名称
System.out.println(summer.toString());
// System.out.println(Season1.class.getSuperclass());
System.out.println("****************");
//values():返回所有的枚举类对象构成的数组
Season1[] values = Season1.values();
for(int i = 0;i < values.length;i++){
System.out.println(values[i]);
}
System.out.println("****************");
Thread.State[] values1 = Thread.State.values();
for (int i = 0; i < values1.length; i++) {
System.out.println(values1[i]);
}
//valueOf(String objName):返回枚举类中对象名是objName的对象。
Season1 winter = Season1.valueOf("WINTER");
//如果没有objName的枚举类对象，则抛异常：IllegalArgumentException
// Season1 winter = Season1.valueOf("WINTER1");
System.out.println(winter);
}
}
//使用enum关键字枚举类
enum Season1 {
//1.提供当前枚举类的对象，多个对象之间用","隔开，末尾对象";"结束
SPRING("春天","春暖花开"),
SUMMER("夏天","夏日炎炎"),
AUTUMN("秋天","秋高气爽"),
WINTER("冬天","冰天雪地");
//2.声明Season对象的属性:private final修饰
private final String seasonName;
private final String seasonDesc;
//2.私有化类的构造器,并给对象属性赋值
private Season1(String seasonName,String seasonDesc){
this.seasonName = seasonName;
this.seasonDesc = seasonDesc;
}
//4.其他诉求1：获取枚举类对象的属性
public String getSeasonName() {
return seasonName;
}
public String getSeasonDesc() {
return seasonDesc;
}
// //4.其他诉求1：提供toString()
//
// @Override
// public String toString() {
// return "Season1{" +
// "seasonName='" + seasonName + '\'' +
// ", seasonDesc='" + seasonDesc + '\'' +
// '}';
// }
3. 实现接口的枚举类
（1）实现接口，在enum类中实现抽象方法。
interface Info
{
void show();
}
enum Season implements Info
{
SPRING("春天","春风又绿江南岸"),
SUMMER("夏天","映日荷花别样红"),
AUTUMN("秋天","秋水共长天一色"),
WINTER("冬天","窗含西岭千秋雪");
private final String seasonName;
private final String seasonDesc;
private SeasonEnum(String seasonName, String seasonDesc)
{
this.seasonName = seasonName;
this.seasonDesc = seasonDesc;
}
public void show()
{
System.out.println("这是一个季节");
}
}
（2）让枚举类的对象分别实现接口中的抽象方法。
public class SeasonTest1 {
public static void main(String[] args) {
Season1 summer = Season1.SUMMER;
//toString():返回枚举类对象的名称
System.out.println(summer.toString());
// System.out.println(Season1.class.getSuperclass());
System.out.println("****************");
//values():返回所有的枚举类对象构成的数组
Season1[] values = Season1.values();
for(int i = 0;i < values.length;i++){
System.out.println(values[i]);
values[i].show();
}
System.out.println("****************");
Thread.State[] values1 = Thread.State.values();
for (int i = 0; i < values1.length; i++) {
System.out.println(values1[i]);
}
//valueOf(String objName):返回枚举类中对象名是objName的对象。
Season1 winter = Season1.valueOf("WINTER");
//如果没有objName的枚举类对象，则抛异常：IllegalArgumentException
// Season1 winter = Season1.valueOf("WINTER1");
System.out.println(winter);
winter.show();
}
}
interface Info{
void show();
}
//使用enum关键字枚举类
enum Season1 implements Info{
//1.提供当前枚举类的对象，多个对象之间用","隔开，末尾对象";"结束
SPRING("春天","春暖花开"){
@Override
public void show() {
System.out.println("春天在哪里？");
}
},
SUMMER("夏天","夏日炎炎"){
@Override
public void show() {
System.out.println("宁夏");
}
},
AUTUMN("秋天","秋高气爽"){
@Override
public void show() {
System.out.println("秋天不回来");
}
},
WINTER("冬天","冰天雪地"){
@Override
public void show() {
System.out.println("大约在冬季");
}
};
//2.声明Season对象的属性:private final修饰
private final String seasonName;
private final String seasonDesc;
//2.私有化类的构造器,并给对象属性赋值
private Season1(String seasonName,String seasonDesc){
this.seasonName = seasonName;
this.seasonDesc = seasonDesc;
}
//4.其他诉求1：获取枚举类对象的属性
public String getSeasonName() {
return seasonName;
}
public String getSeasonDesc() {
return seasonDesc;
}
// //4.其他诉求1：提供toString()
//
// @Override
// public String toString() {
// return "Season1{" +
// "seasonName='" + seasonName + '\'' +
// ", seasonDesc='" + seasonDesc + '\'' +
// '}';
// }
// @Override
// public void show() {
// System.out.println("这是一个季节");
// }