Read text file in java

Question

Hey, I need to read a textfile in java. The problem is that the file has the following format:

Id time1 time2 time3 ...
ID2 time1 time2 time3 ...
         


        

Answer 1

The simplest way would be to read the whole file line by line once, parsing the lines as you go - then you can very easily get "all the IDs" followed by "all the first times" etc.

If the file is too large to do that, you may want to consider writing a tool to change the file structure - open up several files for writing (one per column) then you can read an input line, write the output data to each file, move onto the next line etc. You can do this once and then read each file as and when you need it.