Java: Parse input file and extract column values

Question

Here is a sample input text file:

some text
one more line of text
another line
and one more
1 23 3
2 34 4
5 12 4
3 23 8

I need to extract each column of numerical values and perform some mathematical operation on it.

This is what i have tried till now:

Path inputFile = Paths.get(args[0]);

            try{
                ArrayList<String> lines = (ArrayList<String>) Files.readAllLines(inputFile, Charset.defaultCharset());
                ArrayList<String []> columns = new ArrayList<>();
                for(String line : lines){
                    columns.add(line.split("\\s"));
                }
                // Now for each line you have columns.
                for(String [] s : columns){ 
                    System.out.println(Arrays.toString(s));
                }

But its just not right and i'm unable to move from this deadlock. Any help would be greatly appreciated..

use Integer.parseInt(columns.get(4/*line 4*/)[2/*23*/]) to convert one of those strings to an integer. — aaazalea
– aaazalea, Commented Sep 16, 2013 at 0:45
When I run the code, the output is similar to the Input! I want the values of each column to be copied to an array (i.e 3 arrays for 3 columns) so that I can add/do some calculation the values in the array at later stage. — SuperStar
– SuperStar, Commented Sep 16, 2013 at 0:50
So basically you want to transpose the numbers part of the input? You want the data be stored column wise rather than line wise. — Viktor Seifert
– Viktor Seifert, Commented Sep 16, 2013 at 12:22

Sujoy · Accepted Answer · 2013-09-16 11:02:36Z

1

I would say ...

for(String line : lines){
                // Just add this condition
                if(line.matches("^[0-9]"){
                    // then process the way you want to...
                }   
            }

Hope this helps...

Edited:

Path inputFile = Paths.get(args[0]);

    try{
        ArrayList<String> lines = (ArrayList<String>) Files.readAllLines(inputFile, Charset.defaultCharset());
        ArrayList<String []> columns = new ArrayList<>();
        for(String line : lines){
            if(line.matches("^[0-9]")){
                System.out.println("Line:"+line);
                String[] colms = line.split("\\s+");
                    columns.add(colms);
                for (int i = 0; i < colms.length; i++) {
                    String temp = colms[i];
                    System.out.println("Colmns:"+i+":"+temp);
                    // process temp one by one
                }
            }
        }
    }catch(Exception ex){
        ex.printStackTrace();
        System.out.println("Exception...");
    }

edited Sep 16, 2013 at 11:02

answered Sep 16, 2013 at 0:49

Sujoy

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2 Comments

SuperStar Over a year ago

Now my output is blank!

Sujoy Over a year ago

Edited the answer...not sure why it's blank...could you please debug and let me know...

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