Timestamps with JDBC

TimestampTest.java

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.sql.Timestamp;
import java.time.LocalDateTime;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.util.Calendar;
import java.util.TimeZone;

import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.testcontainers.containers.JdbcDatabaseContainer;
import org.testcontainers.containers.PostgreSQLContainer;

public class TimestampTest {

    @Rule
    public JdbcDatabaseContainer<?> container = new PostgreSQLContainer<>("postgres:11");

    private HikariDataSource dataSource;

    @Before
    public void setUp() {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl(container.getJdbcUrl());
        config.setUsername(container.getUsername());
        config.setPassword(container.getPassword());
        dataSource = new HikariDataSource(config);
    }

    @After
    public void tearDown() {
        dataSource.close();
    }

    @Test
    public void test_abc() throws Exception {
        Calendar utc = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
        LocalDateTime now = LocalDateTime.now(ZoneOffset.UTC);
        System.out.println("Now: " + ZonedDateTime.now());
        System.out.println("Now in UTC: " + LocalDateTime.now());
        System.out.println("UTC: " + LocalDateTime.now(ZoneOffset.UTC));
        System.out.println("JVM - " + TimeZone.getDefault().getID() + " - hours: " + now.getHour());
        try (Connection conn = dataSource.getConnection(); Statement stmt = conn.createStatement()) {
            //stmt.execute("SET TIME ZONE 'UTC'");
            stmt.execute("CREATE TABLE MY_TEST (C1 TIMESTAMP WITH TIME ZONE, " +
                "C2 TIMESTAMP WITHOUT TIME ZONE, " +
                "C3 TIMESTAMP WITH TIME ZONE, " +
                "C4 TIMESTAMP WITHOUT TIME ZONE, " +
                "C5 TIMESTAMP WITH TIME ZONE, " +
                "C6 TIMESTAMP WITHOUT TIME ZONE, " +
                "C7 TIMESTAMP WITH TIME ZONE, " +
                "C8 TIMESTAMP WITHOUT TIME ZONE)");
            try (ResultSet rs = stmt.executeQuery("SELECT current_setting('TIMEZONE');")) {
                while (rs.next()) {
                    System.out.println("Database: " + rs.getString(1));
                }
            }
            try (PreparedStatement ps = conn.prepareStatement("INSERT INTO MY_TEST " +
                "(C1, C2, C3, C4, C5, C6, C7, C8) VALUES " +
                "(?, ?, ?, ?, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP AT TIME ZONE 'UTC', CURRENT_TIMESTAMP AT TIME ZONE 'UTC')")) {
                ps.setTimestamp(1, Timestamp.valueOf(now));
                ps.setTimestamp(2, Timestamp.valueOf(now));
                ps.setTimestamp(3, Timestamp.valueOf(now), utc);
                ps.setTimestamp(4, Timestamp.valueOf(now), utc);
                ps.executeUpdate();
            }
            try (ResultSet rs = stmt.executeQuery("SELECT * FROM MY_TEST")) {
                while (rs.next()) {
                    printResult(rs, utc, "C1", now.getHour(), "setTimestamp(LocalDateTime) -> with TZ");
                    printResult(rs, utc, "C2", now.getHour(), "setTimestamp(LocalDateTime, UTC) -> with TZ");
                    printResult(rs, utc, "C3", now.getHour(), "setTimestamp(LocalDateTime, UTC) -> with TZ");
                    printResult(rs, utc, "C4", now.getHour(), "setTimestamp(LocalDateTime, UTC> -> without TZ");
                    printResult(rs, utc, "C5", now.getHour(), "CURRENT_TIMESTAMP -> with TZ");
                    printResult(rs, utc, "C6", now.getHour(), "CURRENT_TIMESTAMP -> without TZ");
                    printResult(rs, utc, "C7", now.getHour(), "CURRENT_TIMESTAMP @ UTC -> with TZ");
                    printResult(rs, utc, "C8", now.getHour(), "CURRENT_TIMESTAMP @ UTC -> without TZ");
                }
            }
        }
    }

    private static void printResult(ResultSet rs, Calendar utc, String column, int expected, String label) throws SQLException {
        System.out.println("------- " + column + " - " + label);
        System.out.println(rs.getString(column));
        System.out.println("getTimestamp(): " + (rs.getTimestamp(column).toLocalDateTime().getHour() - expected));
        System.out.println("getTimestamp(UTC): " + (rs.getTimestamp(column, utc).toLocalDateTime().getHour() - expected));
    }
}