Main.java

import org.apache.lucene.index.DirectoryReader;
import org.apache.lucene.index.IndexReader;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;

public class Main {
    public static void main(String[] args) throws IOException {
        String luceneIndexPath = "my-elasticsearch/data/nodes/0/indices/eCCAJ-x6SOuN6w7vqr4tGQ/0/index";
        Directory index = FSDirectory.open(Paths.get(luceneIndexPath));

        IndexReader reader = DirectoryReader.open(index);

        System.out.println(reader.maxDoc());
        
        reader.close();
        index.close();
    }
}