Enum类的方法如下图所示
我们来看一下几个常用的方法:
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
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举例说明:
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。
public class SeasonTest01 {
public static void main(String[] args) {
Season1 summer = Season1.SUMMER;
//toString():
System.out.println(summer);
//System.out.println(Season1.class.getSuperclass());
System.out.println("===================================");
//values():
Season1[] values = Season1.values();
for (int i = 0; i < values.length; i++) {
System.out.println(values[i]);
}
}
}
//使用enum关键词枚举类
enum Season1{
//1.提供当前枚举类的多个对象,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;
//3.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 + '\'' +
// '}';
// }
}
运行结果如下:
我们再以线程的状态为例:
public class SeasonTest01 {
public static void main(String[] args) {
Season1 summer = Season1.SUMMER;
//toString():
System.out.println(summer);
//System.out.println(Season1.class.getSuperclass());
System.out.println("===================================");
//values():
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]);
}
}
}
//使用enum关键词枚举类
enum Season1{
//1.提供当前枚举类的多个对象,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;
//3.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 + '\'' +
// '}';
// }
}
运行结果如下图:
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。
public class SeasonTest01 {
public static void main(String[] args) {
Season1 summer = Season1.SUMMER;
//toString():
System.out.println(summer);
//System.out.println(Season1.class.getSuperclass());
System.out.println("===================================");
//values():
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]);
}
System.out.println("=======================================");
//valuesOf(String objName):返回枚举类中对象名是objName的对象
Season1 winter = Season1.valueOf("WINTER");
System.out.println(winter);
}
}
//使用enum关键词枚举类
enum Season1{
//1.提供当前枚举类的多个对象,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;
//3.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 + '\'' +
// '}';
// }
}
运行结果如下:
假如我们将括号里的WINTER写错了写成了WINTER1.那就找不到了。运行结果如下:
我们可以发现如果没有objName的枚举类对象,则抛异常:IllegalArgumentException
感谢观看!!!