Parsing a fixed-width formatted file in Java

Question

I\'ve got a file from a vendor that has 115 fixed-width fields per line. How can I parse that file into the 115 fields so I can use them in my code?

My first thought

Answer 1

Here is the plain java code to read fixedwidth file:

import java.io.File;
import java.io.FileNotFoundException;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;

public class FixedWidth {

    public static void main(String[] args) throws FileNotFoundException, IOException {
        // String S1="NHJAMES TURNER M123-45-67890004224345";
        String FixedLengths = "2,15,15,1,11,10";

        List<String> items = Arrays.asList(FixedLengths.split("\\s*,\\s*"));
        File file = new File("src/sample.txt");

        try (BufferedReader br = new BufferedReader(new FileReader(file))) {
            String line1;
            while ((line1 = br.readLine()) != null) {
                // process the line.

                int n = 0;
                String line = "";
                for (String i : items) {
                    // System.out.println("Before"+n);
                    if (i == items.get(items.size() - 1)) {
                        line = line + line1.substring(n, n + Integer.parseInt(i)).trim();
                    } else {
                        line = line + line1.substring(n, n + Integer.parseInt(i)).trim() + ",";
                    }
                    // System.out.println(
                    // S1.substring(n,n+Integer.parseInt(i)));
                    n = n + Integer.parseInt(i);
                    // System.out.println("After"+n);
                }
                System.out.println(line);
            }
        }

    }

}

Answer 2

/*The method takes three parameters, fixed length record , length of record which will come from schema , say 10 columns and third parameter is delimiter*/
public class Testing {

    public static void main(String as[]) throws InterruptedException {

        fixedLengthRecordProcessor("1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10", 10, ",");

    }

    public static void fixedLengthRecordProcessor(String input, int reclength, String dilimiter) {
        String[] values = input.split(dilimiter);
        String record = "";
        int recCounter = 0;
        for (Object O : values) {

            if (recCounter == reclength) {
                System.out.println(record.substring(0, record.length() - 1));// process
                                                                                // your
                                                                                // record
                record = "";
                record = record + O.toString() + ",";
                recCounter = 1;
            } else {

                record = record + O.toString() + ",";

                recCounter++;

            }

        }
        System.out.println(record.substring(0, record.length() - 1)); // process
                                                                        // your
                                                                        // record
    }

}

Answer 3

I've played arround with fixedformat4j and it is quite nice. Easy to configure converters and the like.

Answer 4

I would use a flat file parser like flatworm instead of reinventing the wheel: it has a clean API, is simple to use, has decent error handling and a simple file format descriptor. Another option is jFFP but I prefer the first one.