Java, search files of given pattern and get the directory names and complete filenames

Question

I am new to Java. Looking for code to search for files with .ofg extension in all the sub-directories of /var/data.

The desired outputs are

• the subdirectory name(s), which has the files with those files
• the full names of the files
• the number of those files in that subdirectory.

There are some tutorials available, but nothing i could find fitting to my code base; like

public class FindFiles {

    int inProcThreshold = 0;

    protected File recurfile(File file) {
        File[] dirlist = file.listFiles();

        for (File f : dirlist) {
            if (f.isDirectory()) {
                return f;
            }
        }

        return null;
    }

    protected int numOfInProcs(String location, int level, int maxdepth) {
        File base = new File(location);
        File[] firstlevelfiles = base.listFiles();

        while (level <= maxdepth) {
            for (File afile : firstlevelfiles) {
                if (afile.isDirectory()) {
                    base = recurfile(afile);
                } else {
                    if (afile.getName().endsWith(".txt")) {
                        inProcThreshold++;
                    }
                }
            }
            level++;
        }

        return inProcThreshold;
    }

    public static void main(String[] args) {
        FindFiles test = new FindFiles();
        String dirToList = "I:\\TEST-FOLDER";
        String ext = ".txt";
        int count = test.numOfInProcs(dirToList, 0, 10);
        System.out.println("Number of txt files are " + count);
    }

}

This is the code I am trying but it returns 0 as output to me. I am trying to search for files with extension.txt in the I:\\TEST-FOLDER subfolders.

Answer 1

Use this filter by giving directory addres in dirName Parameter it will list all directories with extension .ofg

 import java.io.File;
import java.io.FilenameFilter;

public class Filter {

    public File[] finder( String dirName){
        File dir = new File(dirName);

        return dir.listFiles(new FilenameFilter() { 
                 public boolean accept(File dir, String filename)
                      { return filename.endsWith(".ofg"); }
        } );

    }

}

Answer 2

I think what you are looking for is Files.find . Pass it a Predicate which checks that path.toString().endsWith(".ofg"),

It will return a Stream of Path objects representing the matching files. You can extract all the data you want by iterating on this Stream.

Answer 3

If you are not required to write the recursive part yourself (for practice or as task), you could use Files#walkFileTree with a custom implementation of the FileVisitor Interface (As @ Mena proposed in his comment).

Extend the SimpleFileVisitor class (or implement the FileVisitor interface) and provide your code to be executed on each file:

public class OfgFolderCollectingFileVisitor extends SimpleFileVisitor<Path> {

  /** Stores the matching file paths */
  private final List<Path> collectedPaths = new LinkedList<>();


  @Override
  public FileVisitResult visitFile(final Path file, final BasicFileAttributes attrs) throws IOException {
    // check if the current file is an .ofg file
    if (file.toString().endsWith(".ofg")) {
      // it is -> add it's containing folder to the collection
      this.collectedPaths.add(file.getParent());
    }

    return super.visitFile(file, attrs);
  }


  public List<Path> getCollectedPaths() {
    return this.collectedPaths;
  }

}

Then pass an instance of your implementation to Files#walkFileTree and check the collected paths afterwards:

final OfgFolderCollectingFileVisitor visitor = new OfgFolderCollectingFileVisitor();

try {
  Files.walkFileTree(Paths.get("/var/data"), visitor);
} catch (final IOException ex) {
  ex.printStackTrace();
  return;
}

// let's see if something matched our criteria

final List<Path> ofgContainers = visitor.getCollectedPaths();

System.out.printf("Files found: %d%n", ofgContainers.size());

if (!ofgContainers.isEmpty()) {
  System.out.printf("%nContaining directories:%n");

  for (final Path ofgContainer : ofgContainers) {
    System.out.printf("- %s%n", ofgContaininer);
  }
}

Here is some example output (yes, folder2 and it's subfolder contain an .ofg file)

Files found: 3

Containing directories:
- \var\data\folder1\folder1.1
- \var\data\folder2
- \var\data\folder2\folder2.2