Java中的最大枚举元素数
Java 中枚举中允许的最大元素数是多少?
What is the maximum number of elements allowed in an enum in Java?
我想找出 switch 语句中的最大 case 数.由于 switch 中允许的最大原始类型是 int，因此我们有从 -2,147,483,648 到 2,147,483,647 的情况和一种默认情况.但是也允许使用枚举...所以问题..
I wanted to find out the maximum number of cases in a switch statement. Since the largest primitive type allowed in switch is int, we have cases from -2,147,483,648 to 2,147,483,647 and one default case. However enums are also allowed... so the question..
推荐答案
来自 类文件格式规范:
ClassFile 结构(第 4.1 节)的 16 位 constant_pool_count 字段将每个类或每个接口的常量池限制为 65535 个条目.这作为对单个类或接口的总复杂性的内部限制.
The per-class or per-interface constant pool is limited to 65535 entries by the 16-bit constant_pool_count field of the ClassFile structure (§4.1). This acts as an internal limit on the total complexity of a single class or interface.
我相信这意味着在一个类中不能有超过 65535 个命名的事物"，这也会限制枚举常量的数量.
I believe that this implies that you cannot have more then 65535 named "things" in a single class, which would also limit the number of enum constants.
如果看到一个有 20 亿个案例的开关，我可能会杀死任何接触过该代码的人.
If a see a switch with 2 billion cases, I'll probably kill anyone that has touched that code.
幸运的是，这不可能发生:
Fortunately, that cannot happen:
每个非本地、非抽象方法的代码量被限制为 65536 字节，这取决于 Code 属性 (§4.7.3) 和 LineNumberTable 属性 (§4.7.8) 中的 exception_table 中的索引大小) 和 LocalVariableTable 属性 (§4.7.9).
The amount of code per non-native, non-abstract method is limited to 65536 bytes by the sizes of the indices in the exception_table of the Code attribute (§4.7.3), in the LineNumberTable attribute (§4.7.8), and in the LocalVariableTable attribute (§4.7.9).
相关文章