Printing gitignores

Question

I have written a simple program in Java 7 to write the .gitignore of different file types:

import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Scanner;


public class Oye {
    private static final String HELP_TXT = "help.txt";
    private static final String DATA = "gitignore";
    private HashMap<String, String> map = new HashMap<String, String>();

    public Oye() {
    // Eager approach, building the map in the constructor. Is it good?
        File file = new File(DATA);
        if (file.exists()) {
          if (file.isDirectory()) {
              findFiles(file.listFiles());
          }
      } else {
        println("No data folder: " + DATA);
      }
    }

public static void main(String[] args) {
    if (args.length == 0) {
      printFile(HELP_TXT);
      return;
    }

    Oye oye = new Oye();
    if (args[0].equals("ls")) {
        oye.listFiles();
    } else {
        printFile(oye.getFilePath(args[0]));
    }
}

public void findFiles(File[] files) {
    for (File file: files) {
        if (file.isDirectory()) {
            findFiles(file.listFiles());
        } else {
            String fileName = file.getName();
            if (fileName.endsWith(".gitignore")) {
                fileName = fileName.substring(0, fileName.indexOf(".gitignore"));
                map.put(fileName, file.getAbsolutePath());
            }
        }
    }
}

private String getFilePath(String name) {
    if (map.containsKey(name)) {
      return map.get(name);
    } else {
      throw new IllegalArgumentException("No such file: " + name);
    }
}

private static void printFile(String path) {
    Scanner scanner = null;
    try {
        scanner = new Scanner(new File(path));
        String line;
        while (scanner.hasNextLine()) {
            println(scanner.nextLine());
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        scanner.close();
    }
}

private static void println(String txt) {
  System.out.println(txt);
}

private void listFiles() {
    for (String key: map.keySet()) {
        println(key);
    }
}
}

I know that this code is written in a very naive manner, but I want to know how I can improve my code, specifically about better design decisions and better error handling (should I have my own error classes?).

Assumptions:

• Any single .gitignore file can't be more than few hundred lines.
• .gitignore directory contains all the content and isn't deeply nested.

Answer 1

Printing or writing .gitignore files?

Your title says printing, your description says writing, and your code seem to indicate you are merely creating a Map of directory, which has a .gitignore file, to the actual path of the file itself.

Class name

Oye is an unconventional choice for a Java class whose functionality is to display the contents of .gitignore files. Correct me if it actually means that in some foreign language. :)

Directory traversal in Java 7

Pardon my knee-jerk 'are you on Java 8' comment-questions (at least until Java 9 comes out next year...), but you don't have to be on the latest version, at time of writing, to implement the right directory traversal code. It's already made available in Java 7, do look at this quick write-up and the relevant FileVisitor interface. In my opinion, this should be one of the few classes in your simple Java application, you probably do not even require an instance of your Oye class.

Simplification

private static void println(String txt) {
    System.out.println(txt);
}

This method is unfortunately wholly redundant... You should just simply use System.out.println() for now. Remember, you aren't gonna need it. ;)

private static void printFile(String path) {
    // ...
}

Hmms... this entire method can, and should be, replaced by Files.readAllLines(Path, Charset) too...

Answer 2

A few points that could be improved:

• HELP_TXT: is it really worth readability to slim down your code down by a few bytes? HELP_TEXT is better.
  • Same with println's parameter: String txt \$\rightarrow\$ String text
• Oye oye = new Oye(): Sounds like a stereotypical Australian day, if this is the name of your script, perhaps consider a name change. GIT_IGNORER works wonders in the understanding department.
• fileName.substring(0, fileName.indexOf(".gitignore")): there's a magical tool called .replace: filename = filename.replace('.gitignore', '')

• line is redundant and unused:

  try {
      scanner = new Scanner(new File(path));
      String line;
      while (scanner.hasNextLine()) {
          println(scanner.nextLine());
      }