How do you read in a file from a subdirectory in Java?

Question

I have a Folder named Class and its two subdirectories are Lectures and Grades, and within those two subdirectories are txt files. How do I access the subdirectories (and maybe other subdirectories of the subdirectories Lectures and Grades)from the main directory - Class? I know I can use the absolute path in the code, but I would like to start from the starting folder, Class. So far, I have this as my code:

public class Test {
    public static void main(String[] args) {
        File directory = new File("/Users/Desktop/Class");
        File[] folder = directory.listFiles();
        for (File aFile : folder) {
            // Stuck here...
        }
    }
}

Sorry.. I'm new to Java..

Answer 1

You can recursively call the method to read the file in sub directories

public static void main(String[] args) {
    File currentDir = new File("/Users/Desktop/Class"); // current directory
    displayDirectoryFiles(currentDir);
}

public static void displayDirectoryFiles(File dir) {
    try {
        File[] files = dir.listFiles();
        for (File file : files) {
            if (file.isDirectory()) {
                System.out.println("directory:" + file.getCanonicalPath());
                displayDirectoryContents(file);
            } else {
                System.out.println("     file:" + file.getCanonicalPath());
            }
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Handle the exception properly, currently just printing stacktrace