private void fetchNextIfNeeded() {
if (next == null) {
FileTreeWalker.Event ev = walker.next();
while (ev != null) {
IOException ioe = ev.ioeException();
if (ioe != null) throw new UncheckedIOException(ioe);
// END_DIRECTORY events are ignored
if (ev.type() != FileTreeWalker.EventType.END_DIRECTORY) {
next = ev;
return;
}
ev = walker.next();
}
}
}
@Override
public Event next() {
if (!walker.isOpen()) throw new IllegalStateException();
fetchNextIfNeeded();
if (next == null) throw new NoSuchElementException();
Event result = next;
next = null;
return result;
}
/**
* Creates a new iterator to walk the file tree starting at the given file.
*
* @throws IllegalArgumentException if {@code maxDepth} is negative
* @throws IOException if an I/O errors occurs opening the starting file
* @throws SecurityException if the security manager denies access to the starting file
* @throws NullPointerException if {@code start} or {@code options} is {@ocde null} or the options
* array contains a {@code null} element
*/
FileTreeIterator(Path start, int maxDepth, FileVisitOption... options) throws IOException {
this.walker = new FileTreeWalker(Arrays.asList(options), maxDepth);
this.next = walker.walk(start);
assert next.type() == FileTreeWalker.EventType.ENTRY
|| next.type() == FileTreeWalker.EventType.START_DIRECTORY;
// IOException if there a problem accessing the starting file
IOException ioe = next.ioeException();
if (ioe != null) throw ioe;
}
@Override
public boolean hasNext() {
if (!walker.isOpen()) throw new IllegalStateException();
fetchNextIfNeeded();
return next != null;
}
@Override
public void close() {
walker.close();
}