Java-Files：从文本文件中获取特定索引

Question

I have the following directory server/auth/usernames.txt and i want to read all lines and find a specific index of the string called clientusername

I have the following piece of code

File dirFile = new File("auth/");
String clientUsername ="john";
int indexUsername = Files.readAllLines(Paths.get(dirFile.getAbsolutePath() + "usernames.txt")).indexOf(clientUsername);

but this gives me the full path of server/auth/usernames.txt . I want only to get auth/usernames.txt . How to achieve this?

Answer 1

Change dirFile.getAbsolutePath() to dirFile.toPath()

Answer 2

public static void main(String[] args) {
    File f = new File("path-to-your-file-on-your-system!");
    System.out.println(getLineNumber("SlimShady", f));
    System.out.println(getLineNumber("Eminem", f));
    System.out.println(getLineNumber("MomsSpaghetti", f));
    System.out.println(getLineNumber("doodoodoodoo....doooooooooo...dooooooo...can't touch this!", f));

}

private static int getLineNumber(String userName, File usernameFile) {
    boolean found = false;
    int lineCount = -1;
    try (BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(usernameFile)))) {            
        String line;
        while ((line = reader.readLine()) != null && !found) {
            ++lineCount; // increment and get (start at 0)
            found = line.trim().equals(userName); // found it?
        }
    } catch (IOException ex) {
        Logger.getLogger(TestMain.class.getName()).log(Level.SEVERE, null, ex);
    }
    if (!found) {
        // we didn't find it... return -1 (an impossible valid value) to handle that scenario.
        lineCount = -1;
    }
    return lineCount; // found it, what line?
    
}

And running it with only Eminem-related usernames in my totally made-up usernames file (we get a -1 for MC Hammer... apparently we still can't touch this.

run:
1
0
2
-1
BUILD SUCCESSFUL (total time: 0 seconds)