why does executeUpdate return 1 even if no new row has been inserted?

Question

here is my very simple table (Postgres):

CREATE TABLE IF NOT EXISTS PERFORMANCE.TEST
(
test text NOT NULL UNIQUE
);

if I try to insert a String

Answer 1

that was missing:

conn.commit();

(after the executeUpdate())

actually a new row was inserted but the DB rolled back immediately.

Answer 2

executeupdate is for a 'update table set column = value so on'. For insert just call execute of PreparedStatement.