如何检查用户输入的路径是否正确

Question

我需要证明关于用户输入路径。
因为用户给出的不是文件夹路径而是文件路径。程序"fall down".
我知道这是一个错误，但如何确保用户路径正确。

代码:

 class PathAndWord {
    final String path;
    final String whatFind;
    PathAndWord(String path, String whatFind) {
        this.path = path;
        this.whatFind = whatFind;
    }
    boolean isProperlyInitialized() {
        return path != null && whatFind != null;
    }
}
public void askUserPathAndWord() {
    try {
        tryToAskUserPathAndWord();
    } catch (IOException | RuntimeException e) {
        System.out.println("Wrong input!");
        e.printStackTrace();
    } catch (InterruptedException e) {
        System.out.println("Interrupted.");
        e.printStackTrace();
    }
}
private void tryToAskUserPathAndWord() throws IOException, InterruptedException {
    PathAndWord pathAndWord = readPathAndWord();
    if (pathAndWord.isProperlyInitialized()) {
        performScan(pathAndWord, "GameOver.tmp");
        System.out.println("Thank you!");
    } else {
        System.out.println("You did not enter anything");
    }
}
private PathAndWord readPathAndWord() throws IOException {
    System.out.println("Please, enter a Path and Word (which you want to find):");
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
    String path = readPath(bufferedReader);
    String whatFind = readWord(bufferedReader);
    return new PathAndWord(path, whatFind);
}
private String readPath(BufferedReader bufferedReader) throws IOException {
    System.out.println("Please enter a Path:");
    return bufferedReader.readLine();
}
private String readWord(BufferedReader bufferedReader) throws IOException {
    System.out.println("Please enter a Word:");
    return bufferedReader.readLine();
}
private void performScan(PathAndWord pathAndWord, String endOfWorkFileName) throws InterruptedException {
    BlockingQueue<File> queue = new LinkedBlockingQueue<File>();
    File endOfWorkFile = new File(endOfWorkFileName);
    CountDownLatch latch = new CountDownLatch(2);
    FolderScan folderScan = new FolderScan(pathAndWord.path, queue, latch,
            endOfWorkFile);
    FileScan fileScan = new FileScan(pathAndWord.whatFind, queue, latch,
            endOfWorkFile);
    Executor executor = Executors.newCachedThreadPool();
    executor.execute(folderScan);
    executor.execute(fileScan);
    latch.await();
}

问题:

• 如何检查用户输入path是否正确?
• 如果路径不正确显示消息，path is wrong! Try again。
• 能够检查字- whatFind是否正确。
• 前点需要做什么?

Answer 1

private String readPath(BufferedReader bufferedReader) throws IOException {
    boolean ok = false;
    do {
        System.out.println("Please enter a Path:");
        File f = new File(bufferedReader.readLine());
        if(f.exists() && f.isDirectory())
            ok = true;
        else
            System.err.println("Doesn't exist or is not a folder.");
    } while(!ok);
    return f.getAbsolutePath();
}

EDIT:这个方法执行的任务是"从用户中读取路径，该路径存在并且是一个目录"。如果用户输入了无效的路径(不存在或文件)，该方法就会识别出来，警告用户并再次询问他们…一遍又一遍，直到他们回答正确。

如果可以的话，在本地检查数据是一个很好的习惯。当稍后调用该方法时，您可以确保它返回您所期望的结果。