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目录前言 应用 定义 基本Enum特性 Enum的静态导入 Enum中添加新方法 Switch语句中的Enum Enum的继承 EnumSet的使用 EnumMap的使用 常量相关方
枚举是 Java1.5 引入的新特性,通过关键字 enum 来定义枚举类。
enum WeekEnum {
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, weekend
}
enum WeekEnum {
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, weekend;
public static void main(String[] args) {
for (WeekEnum item : WeekEnum.values()) {
System.out.println(item.ordinal());
System.out.println(item.name());
System.out.println(item.getDeclarinGClass());
System.out.println(Enum.valueOf(WeekEnum.class, item.name()));
}
}
}
方法 | 说明 |
---|---|
values() | 可以遍历enum实例,其返回enum实例的数组 |
ordinal() | 返回每个实例在声明时的次序 |
name() | 返回enum实例声明时的名称 |
getDeclaringClass() | 返回其所属的enum类 |
Enum.valueOf() | 根据给定的名称返回相应的enum实例 |
import static com.coisini.SpringBootlearn.WeekEnum.*;
public class WeekEnumTest {
public static void main(String[] args) {
System.out.println(Monday.name()); // Monday
System.out.println(Tuesday.name()); //Tuesday
}
}
public enum WeekEnum {
Monday(1, "周一"),
Tuesday(2, "周二"),
Wednesday(3, "周三"),
Thursday(4, "周四"),
Friday(5, "周五"),
Saturday(6, "周六"),
weekend(7, "周天");
private Integer value;
private String description;
WeekEnum(Integer value, String description) {
this.value = value;
this.description = description;
}
public Integer getValue() { return this.value; }
public String getDesc() { return this.description; }
public String toString() {
return this.getValue() + " " + this.getDesc();
}
public static void main(String[] args) {
for (WeekEnum item : WeekEnum.values()) {
System.out.println(item);
}
}
}
WeekEnum weekEnum = WeekEnum.Friday;
switch (weekEnum) {
case Friday:
System.out.println(weekEnum);
break;
case Saturday:
break;
}
WeekEnum weekEnum = WeekEnum.Friday;
switch(weekEnum) {
// An enum switch case label must be the unqualified name of an enumeration constant
case WeekEnum.Friday:
break;
default:
break;
}
public interface Period {
enum WeekEnum implements Period{
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, weekend
}
enum MonthEnum implements Period{
January, February, March, April, May, June
}
class PeriodTest {
public static void main(String[] args) {
Period week = WeekEnum.Friday;
Period month = MonthEnum.April;
System.out.println(month + " " + week); // April Friday
}
}
}
import java.util.EnumSet;
enum EnumSetTest {
Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, weekend;
public static void main(String[] args) {
EnumSet<EnumSetTest> points = EnumSet.noneOf(EnumSetTest.class);
points.add(Monday);
System.out.println(points); // [Monday]
points.addAll(EnumSet.of(Tuesday, Wednesday));
System.out.println(points); // [Monday, Tuesday, Wednesday]
points = EnumSet.allOf(EnumSetTest.class);
System.out.println(points); // [Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, weekend]
points.removeAll(EnumSet.of(Monday, Tuesday));
System.out.println(points); // [Wednesday, Thursday, Friday, Saturday, weekend]
points = EnumSet.complementOf(points);
System.out.println(points); // [Monday, Tuesday]
}
}
import java.util.EnumMap;
import java.util.Map;
public enum EnumMapTest {
MON, TUE, WED, THU, FRI, SAT, WEE;
public static void main(String[] args) {
EnumMap<EnumMapTest, String> enumMap = new EnumMap<EnumMapTest, String>(EnumMapTest.class);
enumMap.put(MON, "Monday");
enumMap.put(TUE, "Tuesday");
for (Map.Entry<EnumMapTest, String> em : enumMap.entrySet()) {
System.out.println(em.geTKEy() + " " + em.getValue()); // MON Monday TUE Tuesday
}
}
}
public enum EnumAbstract {
MON {
void getDetail() {
System.out.println("Monday");
}
},
TUE {
void getDetail() {
System.out.println("Tuesday");
}
},
WED {
void getDetail() {
System.out.println("Wednesday");
}
};
abstract void getDetail();
public static void main(String[] args) {
for (EnumAbstract ea : EnumAbstract.values()) {
ea.getDetail();
}
}
}
import java.util.stream.Stream;
public enum WeekEnum {
Monday(1, "周一"),
Tuesday(2, "周二"),
Wednesday(3, "周三"),
Thursday(4, "周四"),
Friday(5, "周五"),
Saturday(6, "周六"),
weekend(7, "周天");
private Integer value;
private String description;
WeekEnum(Integer value, String description) {
this.value = value;
this.description = description;
}
public static WeekEnum toWeekEnum(int value) {
return Stream.of(WeekEnum.values())
.filter(item -> item.value == value)
.findAny()
.orElse(null);
}
public static void main(String[] args) {
System.out.println(WeekEnum.toWeekEnum(1)); // Monday
}
}
以上就是java枚举类型-Enum的详细内容,更多关于java Enum的资料请关注编程网其它相关文章!
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