How do I get asynchronous / event-driven LISTEN/NOTIFY support in Java using a Postgres database?

Here's an asynchronous pattern using com.impossibl.postgres.api (pgjdbc-ng-0.6-complete.jar) with JDK 1.8:

import com.impossibl.postgres.api.jdbc.PGConnection;
import com.impossibl.postgres.api.jdbc.PGNotificationListener;
import com.impossibl.postgres.jdbc.PGDataSource;    
import java.sql.Statement;

public static void listenToNotifyMessage() {
    PGDataSource dataSource = new PGDataSource();
    dataSource.setHost("localhost");
    dataSource.setPort(5432);
    dataSource.setDatabase("database_name");
    dataSource.setUser("postgres");
    dataSource.setPassword("password");

    PGNotificationListener listener = (int processId, String channelName, String payload) 
        -> System.out.println("notification = " + payload);

    try (PGConnection connection = (PGConnection) dataSource.getConnection()) {
        Statement statement = connection.createStatement();
        statement.execute("LISTEN test");
        statement.close();
        connection.addNotificationListener(listener);
        while (true){ }
    } catch (Exception e) {
        System.err.println(e);
    }
}

Create a trigger function for your database:

CREATE OR REPLACE FUNCTION notify_change() RETURNS TRIGGER AS $$
    BEGIN
        SELECT pg_notify('test', TG_TABLE_NAME);
        RETURN NEW;
    END;
$$ LANGUAGE plpgsql;

Assign a trigger for every table you want to track:

CREATE TRIGGER table_change 
    AFTER INSERT OR UPDATE OR DELETE ON table_name
    FOR EACH ROW EXECUTE PROCEDURE notify_change();

The official PostgreSQL JDBC driver now has support for LISTEN and NOTIFY, see https://jdbc.postgresql.org/documentation/server-prepare/#listen--notify

I found the most common PostgreSQL driver in Java from org.postgresql, unfortunately, cannot handle callbacks from database. The other option mentioned pgjdbc-ng seems was popular, however it is not maintained in timely manner and have few vulnerable dependencies.

The option I found working best is a pg-client database driver from Vert.x. The essential idea is the client is operate in reactive way. Let’s have a closer look at implementation:

public static void listen(PgConnection connection) {

        connection.notificationHandler(notification ->
            System.out.println("Received " + notification.getPayload() + " on channel " + notification.getChannel()));

        connection
                .query("LISTEN hero_update")
                .execute()
                .onComplete(ar -> System.out.println("Subscribed to channel"));
    }