content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you under the Apache License, Version 2.0 (the
   * "License"); you may not use this file except in compliance
   * with the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.datastax.oss.driver.examples.basic;
  
  import com.datastax.oss.driver.api.core.CqlSession;
  import com.datastax.oss.driver.api.core.cql.ResultSet;
  import com.datastax.oss.driver.api.core.cql.Row;
  
  /**
   * Connects to a Cassandra cluster and extracts basic information from it.
   *
   * <p>Preconditions:
   *
   * <ul>
   *   <li>An Apache Cassandra(R) cluster is running and accessible through the contacts points
   *       identified by basic.contact-points (see application.conf).
   * </ul>
   *
   * <p>Side effects: none.
   *
   * @see <a href="https://docs.datastax.com/en/developer/java-driver/4.0">Java Driver online
   *     manual</a>
   */
  public class ReadCassandraVersion {
  
    public static void main(String[] args) {
  
      // The Session is what you use to execute queries. It is thread-safe and should be
      // reused.
      try (CqlSession session = CqlSession.builder().build()) {
        // We use execute to send a query to Cassandra. This returns a ResultSet, which
        // is essentially a collection of Row objects.
        ResultSet rs = session.execute("select release_version from system.local");
        //  Extract the first row (which is the only one in this case).
        Row row = rs.one();
  
        // Extract the value of the first (and only) column from the row.
        assert row != null;
        String releaseVersion = row.getString("release_version");
        System.out.printf("Cassandra version is: %s%n", releaseVersion);
      }
      // The try-with-resources block automatically close the session after we’re done with it.
      // This step is important because it frees underlying resources (TCP connections, thread
      // pools...). In a real application, you would typically do this at shutdown
      // (for example, when undeploying your webapp).
    }
  }
  