How to find a file recursively in Java?

Question

I am wondering how I would write a recursive program to locate a file in Java that is indicated by a starting path. It should search through a tree for a specified file. If the file is found, the location of the file should be returned. This is what I have so far (not much and still needs basic cleaning up). I need to use these exact methods. I'm mostly confused with what goes in what methods. So I know I need to use:

File f = new File(dirName);

String [] fileList = f.list();

File aFile = new File (dirName + "\\" + fileList[i]);

if (aFile.isDirectory()) {...}

public class FindFile {

If you could help me figure out what method each of those goes in that would be an amazing help!!! I'm just not really understanding the logic of each method. I also have a driver in another class that I need to utilize.

/**
 * This constructor accepts the maximum number of files to find.
 */
public FindFile (int maxFiles)
{
}

/**
 * The parameters are the target file name to look for and the directory to start in.
 * @param  target = target file name, dirName = directory to start in
 */
public void directorySearch (String target, String dirName) {
    File f = new File(dirName);
    String [] fileList = f.list();
    File aFile = new File(dirName + "\\" + fileList[i]);
    if (aFile.isDirectory()) {
    }
    else {
    }
}

/**
 * This accessor returns the number of matching files found.
 * @return number of matching files found
 */
public int getCount () {
    return -1;
}

/**
 * This getter returns the array of file locations, up to maxFiles in size.
 * @return array of file locations
 */
public String [] getFiles () {
    return new String[] {""};
}

/**
 * Prompt the user for max number of files to look for, the directory to start in, and the file name.
 * Then, print out the list of found files with the full path name to the file (including starting
 * directory). In the event of an exception being thrown, driver catches it and provides an appropriate
 * message to the user.
 */
public static void main (String [] args) {
    Scanner keyboard = new Scanner(System.in);
    System.out.println("What is the max number of files to look for?");
    System.out.println("What directory should we start in?");
    Systme.out.println("What is the file name?");
    }

}

Answer 1

You can use java 8 lambda features like this

try (Stream<Path> walkStream = Files.walk(Paths.get("your search directory"))) {
    walkStream.filter(p -> p.toFile().isFile()).forEach(f -> {
        if (f.toString().endsWith("file to be searched")) {
            System.out.println(f + " found!");
        }
    });
}

Answer 2

You need to use recursion to search the file in all the files, directories and sub directories

public static void main(String[] args) {
    boolean found = searchFile(new File("/tmp"), "10174");
    System.out.println(found);
}

private static boolean searchFile(File file, String search) {
    if (file.isDirectory()) {
        File[] files = file.listFiles();
        for (File f : files) {
            boolean found = searchFile(f, search);
            if (found)
                return true;
        }
    } else {
        if (search.equals(file.getName())) {
            return true;
        }
    }
    return false;
}

If the file needs to returned if found

static File searchFile(File file, String search) {
    if (file.isDirectory()) {
        File[] arr = file.listFiles();
        for (File f : arr) {
            File found = searchFile(f, search);
            if (found != null)
                return found;
        }
    } else {
        if (file.getName().equals(search)) {
            return file;
        }
    }
    return null;
}