How to read file line by line in Java 8?

Question

In Java 8 I see new method is added called lines() in Files class which can be used to read a file line by line in Java. Does it work for huge files? I mean can we load first 1000 lines then second set of 1000 lines. I have huge file with 1GB, Will it work?

Could someone share code snippet how to use it?

Answer 1

Does it work for huge files? [...] I have huge file with 1GB, Will it work?

As far as I can see it should work well for big files as well (but I haven't tried):

try(Stream<String> lines = Files.lines(path)){
    lines.filter(...).map(...)....foreach(...);
}

I mean can we load first 1000 lines then second set of 1000 lines.

How many lines are read at one time is implementation specific to Files.lines (which probably uses a BufferedReader, but I might be wrong).

Answer 2

From the API (embolden by me)

Read all lines from a file as a Stream. Unlike readAllLines, this method does not read all lines into a List, but instead

This very strongly suggests that you can use this on any arbitrarily sized file, assuming your code doesn't hold all of the content in memory.