在Java中,我们可以通过关键字enum来声明一个枚举类型。枚举类型可以看作是一种特殊的类,它的实例是有限且固定的。以下是一个枚举类型的例子: enum Weekday { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY } 在这个例子中,我们声明了一个枚举类型Weekday,它包含了一周七天的枚举值。 需要注意...
EnumSet.of() 方法被重载以用于一般用途,它的性能往往优于可变参数版本,并且可以添加 EnumSet.of() 方法来灵活地创建具有任意数量实例的枚举。 此外 EnumSet 提供了像 copyOf 方法 (i),noneOf() 通过复制从其他集合的元素,和创建Java中的特定Enum类型的空EnumSet 创建 EnumSet。 如何用Java实现EnumSet EnumSet是一...
Bit flags, commonly referred to as bit fields, are an efficient way of storing several related boolean values in a single primitive type. Internally represented in binary, you can decide on how large the storage type needs to be - for example, a Java integer will provide you with space for...
静态初始化静态字段：在日常写项目时，很多数据字典常量都需要定义和使用，同时在 Java 面试中，枚举也是...
importjava.util.EnumMap;publicclassEnumMapExample{publicstaticvoidmain(String[] args){// Create an EnumMap that contains all constants of the Car enum.EnumMapcars=newEnumMap(Car.class);// Put some values in the EnumMap.cars.put(Car.BMW, Car.BMW.getPrice()); ...
They are likely (though not guaranteed) to be much faster than their HashSet counterparts. Even bulk operations execute in constant time if their argument is also an enum set. This class is a member of the Java Collections Framework.
import java.util.EnumMap; import java.util.EnumSet; import java.util.Set;publicclassJavaEnumExamples{publicstaticvoidmain(String[] args) throws IOException{ usingEnumMethods(); usingEnumValueOf(); usingEnumValues(); usingEnumInSwitch(ThreadStatesEnum.START); ...
importjava.util.EnumMap; public class EnumMapExample { public static void main(String[] args) { // Create an EnumMap that contains all constants of the Car enum. EnumMap cars = new EnumMap(Car.class); // Put some values in the EnumMap. ...
1.EnumSet是Set接口的一个专门实现,用于枚举类型。它扩展了AbstractSet并实现了Java中的Set接口。EnumSet的几个重要点如下。 EnumSet类是Java集合框架的一个成员,它不是同步的。 EnumSet中的所有元素都必须来自一个枚举类型,这个枚举类型在创建集合时被明确或隐含地指定。
AJniHandleOwnershipindicating how to handlejavaReference Remarks Portions of this page are modifications based on work created and shared by theAndroid Open Source Projectand used according to terms described in theCreative Commons 2.5 Attribution License. ...