Loop invariant for repeated calls to readLine()

Question

I have a while loop (shown below) that continually reads from a file until EOF is reached. I am supposed to write a loop invariant for any non-trivial loop. Is this a trivial loop? If not, what would be a loop invariant for this while loop? I have never written invariants before.

while (line != null) {
    System.out.println(line);
    line = reader.readLine();
}

Answer 1

You can use a fileReader:

while ((line = fileReader.hasNextLine()) != null) {
    String line = fileReader.nextLine(); 
    System.out.println(line);
}

=D