找不到记录

Question

我一直在练习使用Solr，并且制作了一个CRUD应用程序以与Solr集成。但是在运行和查询Solr时，找不到任何记录。我已将数据添加到核心中。我在做什么错了？

下面是我的代码，this is an image of no results

    /* Method To Connecting to Solr */
	public static String getConnection(){
	      String urlString=""; 
		try {
	      //Preparing the Solr client 
	       urlString = "http://localhost:8983/solr/crud"; 
	       solr = new HttpSolrClient.Builder(urlString).build();
		} catch(Exception e){
			e.printStackTrace();
		}  return urlString;
	}
	
	/* Method to Query Data From Solr */
	public static ArrayList<StudentBean> getStudentsListFromDB() throws IOException {
		ArrayList<StudentBean> studentsList = new ArrayList<StudentBean>();
		SolrQuery query = new SolrQuery(CRUD);
		query.setQuery("*:*"); // actual query
		QueryResponse response = null;
		try {
		    response = solr.query(query);
		} catch (SolrServerException e) {
			e.printStackTrace();
		}
		SolrDocumentList studentList = response.getResults();
		System.out.println(studentList.toString());
		return studentsList;
	}