Does Java have a limit on the class name length?

Question

This question came up in Spring class, which has some rather long class names. Is there a limit in the language for class name lengths?

Answer 1

The Java Language Specification states that identifiers are unlimited in length.

In practice though, the filesystem will limit the length of the resulting file name.

Answer 2

No. Java doesn't impose any limit on the class name. But if you interfacing with other systems (e.g. JNI) its better to be on the safe side.

Answer 3

65535 characters I believe. From the Java virtual machine specification:

The length of field and method names, field and method descriptors, and other constant string values is limited to 65535 characters by the 16-bit unsigned length item of the CONSTANT_Utf8_info structure (§4.4.7). Note that the limit is on the number of bytes in the encoding and not on the number of encoded characters. UTF-8 encodes some characters using two or three bytes. Thus, strings incorporating multibyte characters are further constrained.

here:

https://docs.oracle.com/javase/specs/jvms/se6/html/ClassFile.doc.html#88659

Answer 4

With JDK 1.5, the practical limit for class names on Windows XP with 255 -- longer names gave errors in the file system. This was the full name (directory+package+class).

I have not tried JDK 1.6 on Vista or windows 7, hopefully Sun fixed it to be the NTFS limit of 8000 or so.