<dependencies>
  <dependency>
    <groupId>io.stargate.grpc</groupId>
    <artifactId>grpc-proto</artifactId>
    <version>PROTO_VERSION</version>
  </dependency>
  <dependency>
    <groupId>io.grpc</groupId>
    <artifactId>grpc-netty-shaded</artifactId>
    <version>NETTY_VERSION</version>
  </dependency>
</dependencies>

private static final String ASTRA_DB_ID      = "<id>";
private static final String ASTRA_DB_REGION  = "<region>";
private static final String ASTRA_TOKEN      = "<token>";
private static final String ASTRA_KEYSPACE   = "<keyspace>";

public static void main(String[] args)
throws Exception {
  //-------------------------------------
  // 1. Initializing Connectivity
  //-------------------------------------
  ManagedChannel channel = ManagedChannelBuilder
          .forAddress(ASTRA_DB_ID + "-" + ASTRA_DB_REGION + ".apps.astra.datastax.com", 443)
          .useTransportSecurity()
          .build();

  // blocking stub version
  StargateGrpc.StargateBlockingStub blockingStub =
      StargateGrpc.newBlockingStub(channel)
          .withDeadlineAfter(10, TimeUnit.SECONDS)
          .withCallCredentials(new StargateBearerToken(ASTRA_TOKEN));

QueryOuterClass.Response queryString = blockingStub.executeQuery(QueryOuterClass
  .Query.newBuilder()
  .setCql("SELECT firstname, lastname FROM " + ASTRA_KEYSPACE + ".users")
  .build());

<!--Use the latest version from https://search.maven.org/artifact/com.datastax.oss/java-driver-core -->
<dependency>
  <groupId>com.datastax.oss</groupId>
  <artifactId>java-driver-core</artifactId>
  <version>$LATEST_4X_VERSION</version>
</dependency>

mkdir javaProject
cd javaProject
mkdir -p src/main/java
touch src/main/java/ConnectDatabase.java

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;
import java.nio.file.Paths;

public class ConnectDatabase {

   public static void main(String[] args) {
       // Create the CqlSession object:
       try (CqlSession session = CqlSession.builder()
           .withCloudSecureConnectBundle(Paths.get("/path/to/secure-connect-DATABASE_NAME.zip"))
           .withAuthCredentials("clientId","clientSecret")
           .withKeyspace("keyspace_name")
           .build()) {
           // Select the release_version from the system.local table:
           ResultSet rs = session.execute("select release_version from system.local");
           Row row = rs.one();
           //Print the results of the CQL query to the console:
           if (row != null) {
               System.out.println(row.getString("release_version"));
           } else {
               System.out.println("An error occurred.");
           }
       }
       System.exit(0);
   }
}