java - java中如何清除ClassCastException？

Question

public List<LogLineEntry> query(){

    List<LogLineEntry> timeRange = new ArrayList<LogLineEntry>();
       Settings settings = Settings.settingsBuilder().put("cluster.name", "elasticsearch").build();
        Client client = TransportClient.builder().settings(settings).build().addTransportAddress((TransportAddress) new InetSocketTransportAddress(new InetSocketAddress("127.0.0.1", 9300)));

        SearchResponse sResponse = null;
        QueryBuilder qb = QueryBuilders.rangeQuery("lineNumber").from(100).to(200);

        while(sResponse== null|| sResponse.getHits().hits().length != 0){
            int scrollSize=200, i=0;
            sResponse = client.prepareSearch("jsonlogpage")
                    .setTypes("jsonlog")
                       .setQuery(QueryBuilders.matchAllQuery())
                       .setSize(scrollSize)
                       .setFrom(i * scrollSize)
                       .execute()
                       .actionGet();

            for(SearchHit hit : sResponse.getHits()){
                timeRange.add(hit); //add() shows error
            }
            i++;
        }
        return timeRange;

}

我正在使用搜索响应。我在 add() 中遇到错误。

错误:

Exception in thread "main" java.lang.ClassCastException: org.elasticsearch.search.internal.InternalSearchHit cannot be cast to com.example.elasticsearch.LogLineEntry

LogLineEntry是一个pojo类。我的列表是为LogLineEntry创建的，hit变量属于searchHit。所以我无法将 searchHit 变量添加到列表中。我该如何解决这个问题？

Answer 1

您需要将每个 SearchHit 转换为 LogLineEntry 实例。您不能仅将 SearchHit 实例添加到声明为包含 LogLineEntry 实例的 List 中。

因此，在 for 循环中，您需要创建一个 LogLineEntry 的新实例，并用在每个 SearchHit 实例中找到的字段填充它。

        for(SearchHit hit : sResponse.getHits()){
            LogLineEntry entry = new LogLineEntry();
            // populate your new instance
            entry.setXyz(hit.getXyz());
            // do this for each field

            // add the instance to the list
            timeRange.add(entry);
        }