Can Javassist control class file's version?

[ymruan]

Hi,
When I use javassist to transfers class files,I met this problem.When source class files' version is upper to 1.4. the target classes can not be invoked in an applet(JRE 1.4). Get a class.FormatError(extra bytes).
When I change the class version info by myself.(eg. form CAFE BABE 0000 002E... to CAFE BABE 0003 002D... )This problem is not existed.(Because JRE1.4's profilers).
So How can I control the output class file's version?Thanks!

[ymruan]

The classes are not complied by myself!the version info in class files is 0000 002E .

0000 002E means that the version of the class file is 46.0.
JDK 1.4 or older compilers use the version 45.x format.
So my guess is that class file might be compiled by JDK 1.5.

However, I am not sure if this solution would
bring any potential troubles.

I don't think so (at least) unless you use JDK1.5 syntax.

Chiba

[chiba]

What is your compiler? javac of JDK1.5?
JRE 1.4 might refuse a class file generated
by 1.5 compiler.

[ymruan]

Hi professor,
The classes are not complied by myself!the version info in class files is 0000 002E .
The problem can be resolved simply by manually revising the version code. However, I am not sure if this solution would
bring any potential troubles. For instance, is there any differnce in class format for different versions?

[chiba]

The classes are not complied by myself!the version info in class files is 0000 002E .

0000 002E means that the version of the class file is 46.0.
JDK 1.4 or older compilers use the version 45.x format.
So my guess is that class file might be compiled by JDK 1.5.

However, I am not sure if this solution would
bring any potential troubles.

I don't think so (at least) unless you use JDK1.5 syntax.

Chiba