super(); this.driverClass = driverClass; this.connectionUrl = connectionUrl; this.username = username; this.password = password;
this( driverClass, connectionUrl, null, null );
   public JdbcDatabaseTester( String driverClass, String connectionUrl, String username,         String password )   {      super();      this.driverClass = driverClass;      this.connectionUrl = connectionUrl;      this.username = username;      this.password = password;   }