As there isn’t yet an approved answer – the proper way to reset the maxlines property of the TextView is:
textView.setMaxLines(Integer.MAX_VALUE);
As per Valdemar’s comment and this stackoverflow answer. Using -1 will cause an ArrayIndexOutOfBoundsException.
Keep in mind only END and MARQEE setEllipsize() settings will be respected for maxlines >= 2 according to the documentation:
If setMaxLines(int) has been used to set two or more lines, END and
MARQUEE* are only supported (other ellipsizing types will not do
anything).