How can I read a large text file line by line using Java?

Question

I need to read a large text file of around 5-6 GB line by line using Java.

How can I do this quickly?

Answer 1

In Java 8, there is also an alternative to using Files.lines(). If your input source isn't a file but something more abstract like a Reader or an InputStream, you can stream the lines via the BufferedReaders lines() method.

For example:

try (BufferedReader reader = new BufferedReader(...)) {
  reader.lines().forEach(line -> processLine(line));
}

will call processLine() for each input line read by the BufferedReader.