My 1st JDBC and PostgreSQL

Following the example in :
https://www.tutorialspoint.com/postgresql/postgresql_java.htm
I wrote the bellow method :

public void connectToDatabase() throws ClassNotFoundException,
SQLException {
        try {
            this.perr(this.getDatabaseClass()); //
org.postgresql.Driver = Class
            this.perr(this.getDatabaseUrl());   //
jdbc:postgresql://localhost:5432/sara.pgdb = url
            this.perr(this.getUserID());        // chispa = user
            this.perr(this.getUserPassword());  // 8UUKZW = password

            Class.forName(this.getDatabaseClass().toString());
            conn =
DriverManager.getConnection(this.getDatabaseUrl().toString(),
                    this.getUserID().toString(),
                    this.getUserPassword().toString() );
        } catch (final SQLException | ClassNotFoundException e) {
            throw e;
        }
    }

However, it throws an exception that reads :
Exception in thread "main" org.postgresql.util.PSQLException: FATAL:
database "sara.pgdb" does not exist

In reference to the above web page, it reads :
The following Java code shows how to connect to an existing database. If
the database does not exist, then it will be created and finally a
database object will be returned.

True, the database file does not exist, but isn't JDBC supposed to
create it?

Any help would be much appreciated.