import org.apache.lucene.index.IndexFileNameFilter; //导入依赖的package包/类
private void create() throws IOException {
  if (directory.exists()) {
    String[] files = directory.list(IndexFileNameFilter.getFilter());            // clear old files
    if (files == null)
      throw new IOException("cannot read directory " + directory.getAbsolutePath() + ": list() returned null");
    for (int i = 0; i < files.length; i++) {
      File file = new File(directory, files[i]);
      if (!file.delete())
        throw new IOException("Cannot delete " + file);
    }
  }
  lockFactory.clearLock(IndexWriter.WRITE_LOCK_NAME);
}
 

import org.apache.lucene.index.IndexFileNameFilter; //导入依赖的package包/类
/** Returns an array of strings, one for each Lucene index file in the directory. */
public String[] list() {
  ensureOpen();
  return directory.list(IndexFileNameFilter.getFilter());
}
 

import org.apache.lucene.index.IndexFileNameFilter; //导入依赖的package包/类
private LuceneIndexFileNameFilter() {
  luceneFilter = IndexFileNameFilter.getFilter();
}