Number of lines in a file in Java

Question

I use huge data files, sometimes I only need to know the number of lines in these files, usually I open them up and read them line by line until I reach the end of the file<

Answer 1

If you don't have any index structures, you'll not get around the reading of the complete file. But you can optimize it by avoiding to read it line by line and use a regex to match all line terminators.