What to do when the following error pops up in Eclipse while saving a file:

Save could not be Completed
Reason:
Some characters cannot be mapped using “<your-encoding-here>” character encoding.
Either change the encoding or remove the characters which are not supported by the “<your-encoding-here>” character encoding.

If you’re certain that the encoding is correct an you didn’t enter any weired characters, you should copy/paste the content of the file to an external editor and see if it tells you where those hidden, special characters are.

On Linux and Mac you may as well abuse the terminal for that for certain character set. Just paste the code to the shell and see if you find anything unusual.