java - 既にラベル付けされた文字列ラジオ ボタンに値を設定しようとしています。私は自分の間違いを理解していません

Question

public class RoomListener implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {
        double roomtype; 

        if (event.getSource() == room1)
            roomtype = 60;
        else if (event.getSource() == room2)
            roomtype = 75;
        else 
            roomtype = 100;
    }

}


public class CostListener implements ActionListener
{
    public void actionPerformed(ActionEvent event)
    {
        double NightLength, roomNumber, cost;
        String NightText = NumberOfNights.getText();
        String RoomText = NumberOfRooms.getText();

        NightLength = Double.parseDouble(NightText);
        roomNumber = Double.parseDouble(RoomText);

        RoomListener.actionPerformed(RoomType);
        cost = roomtype * NightLength * roomNumber;

        CostCalculation.setText(Double.toString(cost));
        NumberFormat fmt = NumberFormat.getNumberInstance();
        CostCalculation.setText(fmt.format(cost));
    }
}