>>> class AutoName(Enum): ... def _generate_next_value_(name, start, count, last_values): ... return name ... >>> class Ordinal(AutoName): ... NORTH = auto() ... SOUTH = auto() ... EAST = auto() ... WEST = auto() ... >>> list(Ordinal) [<Ordinal.NORTH...
4. 解决“classes cannot directly extend 'java.lang.Enum'”错误的建议 如果你尝试编写一个类来直接扩展 java.lang.Enum,你将会遇到编译错误。解决这个问题的方法是使用Java内置的枚举类型(即使用 enum 关键字),而不是尝试通过继承 java.lang.Enum 来创建枚举。如上例所示,使用 enum 关键字声明枚举类型是一种...
enum may implement many interfaces but cannot extend any class because it internally extends Enum class In the Java programming language, you define an enum type by using the enum keyword. For example, you would specify a days-of-the-week enum type as: public enum Day { SUNDAY, MONDAY, TU...
虽然我们使用 class 语法来创建 Enum,但 Enum 并不是普通的 Python 类。 更多细节请参阅 How are Enums different?。枚举成员具有适合人类阅读的表示形式:>>> >>> print(Color.RED) Color.RED ...而它们的 repr 包含更多信息:>>> >>> print(repr(Color.RED)) <Color.RED: 1> 一...
枚举是使用 class 语法来创建的,这使得它们易于读写。 另一种替代创建方法的描述见 Functional API。 要定义一个枚举,可以对 Enum 进行如下的子类化: >>> >>> from enum import Enum >>> class Color(Enum): ... RED = 1 ... GREEN = 2 ... BLUE = 3 ... 注解 Enum 的成员值 成员值可以...
>>> class Shape(Enum): ... SQUARE = 2 ... SQUARE = 3 ... Traceback (most recent call last): ... TypeError: Attempted to reuse key: 'SQUARE' 但是,允许两个枚举成员有相同的值。 假定两个成员 A 和 B 有相同的值(且 A 先被定义),则 B 就是 A 的一个别名。 按值查找 A 和...
It means that all enums arecomparableandserializableimplicitly. Also, all enum types in Java aresingletonby default. As noted all enums extendsjava.lang.Enum, soenum cannot extend any other classbecause Java does not supportmultiple inheritancethis way. But enums can implement any number of inte...
虽然我们使用 class 语法来创建 Enum,但 Enum 并不是普通的 Python 类。 更多细节请参阅 How are Enums different?。枚举成员具有适合人类阅读的表示形式:>>> >>> print(Color.RED) Color.RED ...而它们的 repr 包含更多信息:>>> >>> print(repr(Color.RED)) <Color.RED: 1> 一...
Note:Allenums implicitly extendjava.lang.Enum. Because a class can only extend one parent (seeDeclaring Classes), the Java language does not support multiple inheritance of state (seeMultiple Inheritance of State, Implementation, and Type), and therefore an enum cannot extend anything else. ...
A Java enumeration is a class type. Although we don’t need need to instantiate an enum usingnew,it has the same capabilities as other classes. This fact makes Java enumeration a very powerful tool. Just like classes, you can give them constructor, add instance variables and methods, and ...