I don’t know how to use some Roboto character in my Textview.
I tried to copy paste character from the character table to eclipse (Roboto is also in my ubuntu), it works for some one but for all…
The greek ‘k’ works, but the greek ‘h’ do not print anything, ..
What is the good way to use all special characters in an android project please?

You probably need to use the unicode values of those characters vs copying pasting them from somewhere…
E.g:
Get the unicode value of a character (using LibreOffice for example), and use that in your strings.xml with the ‘\u’ prefix:
See my screenshot (using Roboto-Black.ttf)
