Java-Files：从文本文件中获取特定索引答案

【问题标题】：Java-Files: get specific index from text fileJava-Files：从文本文件中获取特定索引
【发布时间】：2021-01-12 14:21:41
【问题描述】：

我有以下目录server/auth/usernames.txt，我想读取所有行并找到名为clientusername的字符串的特定索引

我有以下代码

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

但这给了我server/auth/usernames.txt 的完整路径。我只想得到auth/usernames.txt。如何做到这一点？

【问题讨论】：

标签： java file path

【解决方案1】：

将dirFile.getAbsolutePath() 更改为dirFile.toPath()

【讨论】：

【解决方案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?
    
}

在我完全编造的用户名文件中只使用与 Eminem 相关的用户名运行它（MC Hammer 得到 -1 ......显然我们仍然无法触及这个。

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

【讨论】：