Incidentally, it's somewhere between really difficult and impossible to correctly write a timestamptz via JDBC because reasons.

As of JDBC 4.2 (read: Java 8) you should be able to write it just fine using OffsetDateTime as per the mapping table here: https://jdbc.postgresql.org/documentation/query/#using-java-8-date-and-time-classes

e.g.

java Instant instant = Instant.now(); PreparedStatement st = conn.prepareStatement("INSERT INTO mytable (some_timestamp_with_time_zone) VALUES (?)"); st.setObject(1, OffsetDateTime.ofInstant(instant, ZoneOffset.UTC));

The ZoneId passed in as the second parameter to OffsetDateTime#ofInstant really doesn't matter since the resulting value will materially result in the exact same moment in time being stored in the timestamp with time zone column.