You may develop your code using any implementation of the Java 2 platform, but the submission that you return must have been tested and shown to work under a production (not development) version of the Sun Microsystem's Java 2 platform and that platform must not have been superseded by a new production version for more than 18 months by the time you make your submission.
Summarizing the above:
(1) You can use any
Java 2 to develop.
(2) Your code should be successfully compiled using Java 5.0.
(3) Then, the program should run correctly on Java 5.0.
In your case:
You don't have to worry about (1) as you used J2SDK 1.4.x which is Java 2.
For (2), download/install J2SDK 5.0 and see if your codes compile using J2SDK. There might be minor compilation errors (for example, if you used "enum", which is a keyword as of Java 5.0, as a variable name); then, fix them.
And then, for (3), run your application by executing:
It will work as it did on Java 1.4.x!!
So nothing to worry about...
Chulwoo