What's the limit to the number of members you can have in a java enum?

Assuming you have a hypothetical enum in java like this (purely for demonstration purposes, this isn't code i'm seriously expecting to use):

enum Example{
    FIRST,
    SECOND,
    THIRD,
    ...
    LAST;
}

What's the maximum number of members you could have inside that enum before the compiler stops you?

Secondly, is there any performance difference at runtime when your code is referencing an enum with say, 10 members as opposed to 100 or 1,000 (other than just the obvious memory overhead required to store the large class)?

Solution

The best way to find out the answer to this type of question is to try it. Start with a little Python script to generate the Java files:

n = input()
print "class A{public static void main(String[] a){}enum B{"
print ','.join("C%d" % x for x in range(n))
print '}}'

Now try with 1,10,100,1000... works fine, then BAM:

A.java:2: code too large C0,C1,C2,C3,C4,C5,C6,C7,C8,C9,C10,C11,C12,C13,C14,C15,C16,C17,C18,C19,C20,C21,C22,...

Seems like I hit some sort of internal limit. Not sure if it's a documented limit, if it's dependent on the specific version of my compiler, or if its some system dependant limit. But for me the limit was around 3000 and appears to be related to the source code size. Maybe you could write your own compiler to bypass this limit.