hi Asra,
your code might make sense for your project,
but please understand that you should post code here what is complete,can run,
and is just about the problem.
so i try:
String outfile = "data/text.txt";
String[] vals = {"line1","line2"};
saveStrings(outfile,vals);
from the PDE under windows 10 / processing 3.5.3
and the directory “data” was created automatically and the file with 2 lines saved.
so, now you try that 3 lines in your Android environment, i can NOT answer about that.