public class ConnectionFactory {

private String url = "jdbc:postgresql://localhost:5432/aluno";
private String user = "postgres";
private String password = "";

public Connection getConnection(){
    try{
        Class.forName("org.postgresql.Driver");
        return DriverManager.getConnection(url, user, password);
    } catch (SQLException | ClassNotFoundException e){
        throw new RuntimeException(e);

return DriverManager.getConnection(url, user, password);

public AlunoDAO(){
    if(connection == null){
        connection = new ConnectionFactory().getConnection();
    }
}

connection.getConnection()