java - Parse .txt to .csv

Question

Is it possible to create a Java program which recognizes the text in a .txt file and write it in a .csv file? If yes,how would you start with such a problem?

My .txt file is Text1 |Text 2 so I could somehow get the char "|" and split it into two cells.

Answer 1

This is very simple in Java 8:

public static void main(String[] args) throws Exception {
    final Path path = Paths.get("path", "to", "folder");
    final Path txt = path.resolve("myFile.txt");
    final Path csv = path.resolve("myFile.csv");
    try (
            final Stream<String> lines = Files.lines(txt);
            final PrintWriter pw = new PrintWriter(Files.newBufferedWriter(csv, StandardOpenOption.CREATE_NEW))) {
        lines.map((line) -> line.split("\|")).
                map((line) -> Stream.of(line).collect(Collectors.joining(","))).
                forEach(pw::println);
    }
}

First you get your files at Path objects.
Then you open a PrintWriter to your destination Path.

Now you do some Java 8 stream processing with lambdas:

• Files.lines(txt) streams the lines from the file
• map((line) -> line.split("\|")) splits each line to a String[] on |
• map((line) -> Stream.of(line).collect(Collectors.joining(","))) joins the individual String[] again using ,
• forEach(pw::println) writes the new lines to the destination file.

Using import static:

    try (
            final Stream<String> lines = Files.lines(txt);
            final PrintWriter pw = new PrintWriter(newBufferedWriter(csv, StandardOpenOption.CREATE_NEW))) {
        lines.map((line) -> line.split("\|")).
                map((line) -> Stream.of(line).collect(joining(","))).
                forEach(pw::println);
    }

As Java 8 was released only yesterday here is a Java 7 solution:

public static void main(String[] args) throws Exception {
    final Path path = Paths.get("path", "to", "folder");
    final Path txt = path.resolve("myFile.txt");
    final Path csv = path.resolve("myFile.csv");
    final Charset utf8 = Charset.forName("UTF-8");
    try (
            final Scanner scanner = new Scanner(Files.newBufferedReader(txt, utf8));
            final PrintWriter pw = new PrintWriter(Files.newBufferedWriter(csv, utf8, StandardOpenOption.CREATE_NEW))) {
        while (scanner.hasNextLine()) {
            pw.println(scanner.nextLine().replace('|', ','));
        }
    }
}

Again, with import static:

    try (
            final Scanner scanner = new Scanner(newBufferedReader(txt, utf8));
            final PrintWriter pw = new PrintWriter(newBufferedWriter(csv, utf8, StandardOpenOption.CREATE_NEW))) {
        while (scanner.hasNextLine()) {
            pw.println(scanner.nextLine().replace('|', ','));
        }
    }