Applications for a variety of working with office formats under Android already very much, but sometimes you just have to work with simple text files,for example just txt.
In this You soon may be useful Jota Text Editor is a good text editor designed specifically for easy work with different text files, especially large in size and also has a wide functionality.
the List of supported encodings
the Developers promise that Jota will not contain advertising and is absolutely free!
also requested to pay attention to the fact that there is no language support from right-to-left and bidirectional text.