How do I scan a folder in Java?

Question

I need to scan a particular folder in Java, and be able to return the integer number of files of a particular type (based on not only extension but also naming convention.) For example, I want to know how many JPG files there are in the \src folder that have a simple integer filename (say, 1.JPG through 30.JPG). Can anyone point me in the right direction? Thx

Answer 1

java.io.File.list(FilenameFilter) is the method you're looking for.

Answer 2

I have a method that uses a regex pattern for a rather complicated file structure. Something like that could be used, although I'm sure it could be written more concisely than my example (edited for security).

/**
     * Get all non-directory filenames from a given foo/flat directory
     * 
     * @param network
     * @param typeRegex
     * @param locationRegex
     * @return
     */
    public List<String> getFilteredFilenames(String network, String typeRegex, String locationRegex) {

        String regex = null;

        List<String> filenames = new ArrayList<String>();
        String directory;

        // Look at the something network
        if (network.equalsIgnoreCase("foo")) {

            // Get the foo files first
            directory = this.pathname + "/" + "foo/filtered/flat";
            File[] foofiles = getFilenames(directory);

            // run the regex if need be.
            if (locationRegex != null && typeRegex != null ) {
                regex = typeRegex + "." + locationRegex;

                //System.out.println(regex);
            }


            for (int i = 0; i < foofiles.length; i++) {
                if (foofiles[i].isFile()) {
                    String file = foofiles[i].getName();

                    if (regex == null) {
                        filenames.add(file);
                    }
                    else {
                        if (file.matches(regex)) {
                            filenames.add(file);
                        }
                    }
                }
            }
        }

        return filenames;
    }