You just forgot to create the keyspace.
Full code used to create a KS, create a CF and use the querybuilder to insert a partition.
public static void main(String[] Args)
{
Cluster cluster = null;
cluster = Cluster.builder()
.addContactPoint("127.0.0.1")
.build();
Session session = cluster.connect();
try
{
String createKS = "CREATE KEYSPACE test WITH REPLICATION = { 'class': 'SimpleStrategy', 'replication_factor': '2' }";
session.execute(createKS);
String query = "create table test.user (username text primary key,first text, last text);";
session.execute(query);
System.out.println("insert executed");
Insert insert = QueryBuilder.insertInto("test", "user")
.value("username", "jdoe")
.value("first", "John")
.value("last", "Doe");
System.out.println(insert.toString());
ResultSet result = session.execute(insert.toString());
System.out.println(result);
}
catch (Exception ex)
{
ex.printStackTrace();
}
System.exit(0);
}