在Java中解析拆分的CSV文件

Question

i have a csv file with comments, the values of which need to be split between two ArrayLists. eg:

% the values below here should go
% into ArrayList<Integer> list1
3,4,5,2,2,3
5,6,3,2,4,5
3,2,3,4,5,6
2,3,4,5,1,3
% the values below here should go
% into ArrayList<Integer> list2
4,6,3,4,5,3
3,4,5,6,3,2
4,5,6,4,3,2

what is the best way of achieving this? should i use a counter that is incremented each time the state changes from % to a value or vice versa and then if counter % 2 = 0 then add a new ArrayList and start writing to that? thats the only way i can think to do it, but it seems a little bit clumsy, does anyone else have a better idea?

EDIT: i have already written the code for actually parsing the csv values, i dont need help with that, just wondering about how to split the values into two lists..

Answer 1

Your suggestion sounds good to me. If the file format is really so predictable, any more sophisticated approaches might just be overkill in my opinion.

But if you want to see a different approach, this is my idea: Every line that does not start with an % is something we want to parse to an ArrayList . So, whenever you come across a line that is not a comment, you start parsing the following lines to an ArrayList until you either hit another comment or the end of the file. Both options mark the end of the part that you want to store in one single ArrayList . So, something like this:

ArrayList<ArrayList<Integer>> arrays = new ArrayList<ArrayList<Integer>>();
ArrayList<Integer> currentArray;
while(inputStream.hasNextLine()) {
    String line = inputStream.getLine();
    if(!lineIsComment(line)) {
        // This means that we are in a number block. We store the numbers
        // either in an existing list or create a new one if necessary
        if(currentArray == null) {
            currentArray = new ArrayList<Integer>();
        }
        addToList(line, currentArray);
    } else if(currentArray != null) {
        // In this case a comment block starts and currentArray contains
        // the numbers of the last number block.
        arrays.add(currentArray);
        currentArray = null;
    }
}
if(currentArray != null) arrays.add(currentArray);

where lineIsComment(String line) returns a boolean that indicates whether the given line is a comment, and addToList(String line, ArrayList<Integer> list) uses your method to parse a line of numbers and stores them in the provided list.