问在for循环中使用WriteBatch会产生错误

EN

java.lang.IllegalStateException: A write batch can no longer be used after commit() has been called.

private void addData2DB(ArrayList<String> titles, ArrayList<String> authors, ArrayList<String> publishers, ArrayList<String> genres, ArrayList<String> pages) {
    db = FirebaseFirestore.getInstance();
    WriteBatch batch = db.batch();
    double counter = 1.0;

    for (int i = 0; i <= titles.size(); i++) {

        Map<String, Object> data = new HashMap<>();
        String title = titles.get( i );

        String[] TitleWords = title.split( "\\s+" );

        if (!title.isEmpty()) {
            String docID = db.collection( "GeneratingID" ).document().getId();

            data.put( "bookAuthor", authors.get( i ) );
            data.put( "bookTitle", titles.get( i ) );
            data.put( "genre", genres.get( i ) );
            data.put( "pages", pages.get( i ) );
            data.put( "publishedBy", publishers.get( i ) );

            DocumentReference dr = db.collection( "BooksDB" ).document( docID );
            batch.set( dr, data );
        }

        if ((double) i / 500 == counter) {
            batch.commit();
            counter = counter + 1;
        }
    }

}