how to connect to PostgreSQL server to query the database names list

Ok. I have figured it out my self. I can use this string to connect to the server with jdbc driver.

jdbc:postgresql://localhost:5432/?

and can use this code snippet to get the database list

private void listDownAllDatabases() {        try {            PreparedStatement ps = connection                    .prepareStatement("SELECT datname FROM pg_database WHERE datistemplate = false;");            ResultSet rs = ps.executeQuery();            while (rs.next()) {                System.out.println(rs.getString(1));            }            rs.close();            ps.close();        } catch (Exception e) {            e.printStackTrace();        }    }

References: I used this dba stackexchange answer to get all the database list

AFAIK, that is beyond the capabilities of JDBC. I suggest you reconsider your approach to the bigger problem. Environment variables or a PROPERTIES file might be a solution.

import java.io.PrintStream;import java.sql.Connection;import java.sql.DriverManager;import java.sql.ResultSet;import java.sql.Statement;/** * Dev Parzival */public class TestingDatabase {    static String driver="org.postgresql.Driver";    static String jdbc_url="jdbc:postgresql://localhost:5432/";    static String username="username",password="password";    static PrintStream out;    static{        out=System.out;    }    public static void main(String $[]){        //SELECT datname FROM pg_database        try{            Class.forName(driver);            Connection connection= DriverManager.getConnection(jdbc_url,username,password);            Statement statement=connection.createStatement();            ResultSet result=statement.executeQuery("SELECT datname FROM pg_database");            while(result.next()){                System.out.println(result.getString(1));            }            connection.close();        }catch(Exception ex){            ex.printStackTrace();        }    }}

Hope this might help someone somehow