Java中枚举元素的最大数量 [英] Maximum number of enum elements in Java

问题描述

我想了解一个switch语句中最大的个案数量。由于switch中允许的最大的原始类型是int，因此我们有-2,147,483,648到2,147,483,647的情况，一个是默认的情况。但是枚举也被允许...所以问题..

解决方案

从类文件格式规格：

每个类或每个接口常量池由ClassFile结构的16位constant_pool_count字段限制为65535个条目（§4.1）。这对单一类或接口的整体复杂性构成内部限制。

我相信这意味着你不能有更多的那么65535在单个类中命名为东西，这也将限制枚举常量的数量。

如果看到一个带有2幸运的是，这不可能发生：

$ b

每个非本机非抽象方法的代码量通过Code属性的exception_table中的索引大小限制为65536个字节（§4.7 .3），LineNumberTable属性（§4.7.8）和LocalVariableTable属性（§4.7.9）中。

What is the maximum number of elements allowed in an enum in Java?

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..

解决方案

From the class file format spec:

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.

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.

If a see a switch with 2 billion cases, I'll probably kill anyone that has touched that code.

Fortunately, that cannot happen:

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).

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