import java.io;

File dir = new File("directoryName");

String[] children = dir.list();
if (children == null) {
    // Either dir does not exist or is not a directory
} else {
    for (int i=0; i<children.length; i++) {
        // Get filename of file or directory
        String filename = children[i];
    }
}

import java.io;

File dir = new File("directoryName");

// List of returned files can be filtered.
// This example does not return any files that start with `.'.
FilenameFilter filter = new FilenameFilter() {
    public boolean accept(File dir, String name) {
        return !name.startsWith(".");
    }
};
String[] children = dir.list(filter);

import java.io;

File dir = new File("directoryName");

// The list of files can also be retrieved as File objects
File[] files = dir.listFiles();

// This filter only returns directories
FileFilter fileFilter = new FileFilter() {
    public boolean accept(File file) {
        return file.isDirectory();
    }
};
files = dir.listFiles(fileFilter);