private String nextLine() {
        String line = null;
        try {
            line = reader.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        return line;
    }
Constructor for a crawler that reads a list of files to process.
<p>
The list should be paths relative to the root.

@param fileQueue    queue for batch
@param numConsumers number of consumers
@param root         root input director
@param list         text file list (one file per line) of paths relative to
                    the root for processing
@param charset      charset of the file
@throws IOException
tika-batch/src/main/java/org/apache/tika/batch/fs/FSListCrawler.java