package reader;

public abstract class Production {
   int sel;
   int fId;
	public abstract String toString();
 
	  }


package reader;

public abstract class Production {
   int sel;
   int fId;
	public abstract String toString();
 
	  }

public abstract class Production {
    int sel;
    int fId;
    public abstract String toString();
}

Fix the Production class (was empty ?!?)