Connection banco Postgres

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

/**
 * A JDBC SELECT (JDBC query) example program.
 */
class Query {
    private static Connection conn;

    public static List<String> main(String[] args) throws SQLException {
        
        List<String> nomes = new ArrayList<String>();

        if (conn == null) {

            try {
                // Carrega a classe do driver JDBC
                // Postgres
                Class.forName("org.postgresql.Driver");
                String url = "jdbc:postgresql://localhost:5432/NomeDoBancoDeDados";
                conn = DriverManager.getConnection(url, "usuarioBD", "senhaBD");
                Statement stmt = conn.createStatement();
                ResultSet rs;
                rs = stmt.executeQuery("select NM_USUARIO from TAB_USUARIO where CD_USUARIO = '1101' order by DH_ATUALIZACAO desc");

                while (rs.next()) {
                    nomes.add(rs.getString("NM_USUARIO"));
                }

            } catch (ClassNotFoundException e) {
                System.out.print("O driver não foi importado ");
                e.printStackTrace();
            } catch (SQLException sqlex) {
                System.err.println(sqlex.getMessage());
            } catch (Exception e) {
                System.out.print("Erro de conexão com o banco ");
                System.err.println(e.getMessage());
            } finally {
                conn.close();
            }
        }
        return nomes;
    }
}

package br.com.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class ConnectionFactory {
	public Connection getConnection(){
		System.out.println("Conectando ao banco ....");
		try{
			
			return DriverManager.getConnection("jdbc:postgresql://localhost:5432/nome do seu banco/","postgres","senha");	
			
		}catch (SQLException e){
			throw new RuntimeException (e);			
		}
	}

}