Those are letters. I think the easiest way to use them is to change the language of the keyboard on your PC. Which editor are you using? The command prompt on DOS/Windows doesn't support all those characters and may print something peculiar instead.
Excellent suggestion Jesper! Just an additional comment if you don't want to manually copu/paste characters most of them have a shortcut associated. charmap will show it in bottom right (if applicable Alt + ...). You just hold down Alt and type the number like Alt + 0212 then release Alt and Presto! Please be sure to select the correct font as well (to match the editor font in Eclipse) as character mappings may be different
But I still think it might be easier to change your keyboard language; I have mine set to German and English (UK) and it occasionally changes spontaneously and this sort of character appears mzsteriouslzÖ öäüß.