Changing password on PostgreSQL

When running my Java app I get...

uki@.. $ java -jar ./build/libs/XYZ-1.0.jar 

Vacuum 'gps_points' table...

org.postgresql.util.PSQLException: FATAL: password authentication failed for user "postgres"

FIX:

uki@.. $ psql -d polygons --user=postgres -c "ALTER USER Postgres WITH PASSWORD 'my_secret';"

ALTER ROLE