Eclipse won't compile, bad class file, wrong version

Question

I am trying to compile code checked out of SVN from another developer. Eclipse has been giving me a lot of trouble lately.

Here are my project-specific settings:

Answer 1

bad class file: C:\Program Files\Java\jre1.6.0_07\lib\rt.jar(java/io/IOException.class)
class file has wrong version 49.0, should be 48.0

It is telling that the mentioned class file is been compiled using a compiler which generates class files of version 49.0, while ant expects it to be compiled using a compiler which generates class files of version 48.0. Since the class in question is part of the JRE, you need to update the classpath in your build.xml to include the JRE containing class files of version 48.0.