It's not quite clear to me, whether the insertion of a new line is desired as the enter key produces it in e.g. notepad. In that case uval's answer seems fine, besides you might want to remember the current position of the cursor before inserting:
int position = editText.getSelectionStart(); editText.getText().insert(position, "\n"); editText.setSelection(position + 1);
Otherwise, if you just want to jump around in the text, as you can do with the arrow keys in notepad, you'll probably have to calculate the number of characters per line at the given width of your view and the size of its text and then get the number and position of the following line accordingly.