In order for the code bellow to work:
► Make sure to update the variables ("solrUrl", "collectionName", ...) with your information.

Search documents using the request handler /select:

final String SELECT_REQUEST_PATH = "/select";

final String[] solrUrl = { "http://localhost:8983/solr" };

final String collectionName = "collection1";

final CloudSolrClient cloudSolrClient = new CloudSolrClient.Builder(Arrays.asList(solrUrl)).build();

cloudSolrClient.setDefaultCollection(collectionName);

// selecting documents [/select] [ModifiableSolrParams]
{
    final ModifiableSolrParams modifiableSolrParams = new ModifiableSolrParams();

    modifiableSolrParams.add(CommonParams.Q, "*:*");
    modifiableSolrParams.add(CoreAdminParams.COLLECTION, collectionName);

    final QueryRequest queryRequest = new QueryRequest(modifiableSolrParams, METHOD.POST);

    queryRequest.setPath(SELECT_REQUEST_PATH);

    final QueryResponse queryResponse = queryRequest.process(cloudSolrClient);

    System.out.println(queryResponse);
}

cloudSolrClient.close();