Strategic Asset Management

I recently came across an interesting little bug with the Java compiler. On my Maximo development environment, I have Eclipse installed with Java 1.6. I use the compiler compliance level to make class files for both Maximo 7 (which is Java 1.5) and Maximo 6 (which is Java 1.4). However, when working on a class file for 1.4 level, I had the following lines of code.

String color = “blue”;
color = color.replace(“e”,”u”);

The above lines of code compiles without error and when tested on a JVM 1.5 or higher, runs without error. However, when I try to run this on a JVM 1.4, I get the error:

Method not found “color.replace”

This was a bit of a surprise to me since I know that replace does exist for JVM 1.4. After a bit of research I found my problem. (Bonus points if you can see it.) The problem is that in JVM 1.4, the only replace method for the String object only takes chars not strings. Java added the strings version in 1.5. I understand my bug and was easy to fix. What got me was that the compiler did not catch it, even though it was supposed to be making sure my end class was was 1.4 compliant.

Moral of the store is watch carefully when you are using Java compliance levels on your projects. It might not be doing such a good job for you.