package archiver.util; import java.io.File; import java.util.ArrayList; import java.util.Arrays; import java.util.Iterator; import java.util.List; public class FileIterator implements Iterator<File>, Iterable<File> {  private Iterator<String> iterator;  private List<String>  paths;  private List<File>   dirs;  public FileIterator(List<String> paths) {   this.paths = new ArrayList<String>(paths);   this.dirs = new ArrayList<File>();   this.iterator = this.paths.iterator();  }  public File next() {   File file = null;   if (hasNext()) {    file = new File(iterator.next());    if (file.isDirectory()) {     dirs.add(file);    }   }   return file;  }  public boolean hasNext() {   if (!iterator.hasNext()) {    paths.clear();    for (File dir : dirs) {     for (String name : dir.list()) {      paths.add(dir.getPath()+File.separator+name);     }    }    dirs.clear();    if (paths.size() == 0) {     return false;    }    iterator = paths.iterator();   }   return true;  }  @Override  public void remove() {   throw new UnsupportedOperationException();  }  @Override  public Iterator<File> iterator() {   return this;  }  public static void main(String[] args) {   FileIterator iter = new FileIterator(Arrays.asList("."));   for (File file : iter) {    System.out.println(file);   }  } }