PostgreSQL-9.6.1 and openjdk-8u91_b14 are installed on my Slackware-14.1 system and I am trying to use schemaSpy_5.0.0.jar on a couple of databases. I have downloaded postgresql-9.4.1212.jre6.jar but cannot get schemaSpy to run.
1) Is the -9.4.1212 version of the driver compatible with postgres-9.6.1? If not, is there a working alternative?
Should work. The 9.4 doesn't imply server compatability.
2) My databases are used by only me. All non-postgres-installed databases are owned by me so neither a username nor a password is required for me to access them. My login name is used by psql to allow me access. Is the lack of a password preventing the driver from functioning? If so, is there a way to inform it that no password is required here?
The default for PostgreSQL is to listen on Unix sockets. JDBC doesn't talk to Unix sockets - it only uses TCP/IP sockets. You need to configure the database to listen on an IP address and port and point to that. You also need to ensure pg_hba.conf and/or have a password on the user JDBC is using (changing to "trust" might work).
