//Bill subclass
public class VariableBill extends Bill
{
  private String variableBillDesc; //describes expense
  private String variableBillDetails; //description of bills details

  //all variables set to neutral default values
  public VariableBill()
  {
    variableBillDesc = null;
    variableBillDetails = null;
  }

  //constructor for VariableBill object, sets values for variables
  public VariableBill(String owedTo, String owedFor, double owedAmt, String owedWhen, String owedPaidDate,
                   String owedDesc, String owedDetails)
  {
    setBiller(owedTo);
    setBillAcct(owedFor);
    setBillAmtDue(owedAmt);
    setBillDueDate(owedWhen);
    setVariableBillDesc(owedDesc);
    setBillPaidDate(owedPaidDate);
    setVariableBillDetails(owedDetails);
  }

  //sets variableBillDesc
  public final void setVariableBillDesc(String owedDesc)
  {
    variableBillDesc = owedDesc;
  }

  //sets variableBillDetails
  public final void setVariableBillDetails(String owedDetails)
  {
    variableBillDetails = owedDetails;
  }

  //returns variableBillDesc
  public final String getVariableBillDesc()
  {
    return variableBillDesc;
  }

  //returns variableBillDetails
  public final String getVariableBillDetails()
  {
    return variableBillDetails;
  }

  //returns string output containing bill information, paid status, and its detailed info
  public String toString()
  {
    String output = String.format(getBiller() + " is owed $" + getBillAmtDue() +" on account " + getBillAcct()+ " by " + getBillDueDate()+"\n");
    if(getBillPaidDate() == null) //checks if bill has been paid
    {
      output += "This bill has not yet been paid.";
    } else
    {
     output += "This bill was paid on "+ getBillPaidDate() +".";
    }
    output += "\nThis bill is for " + getVariableBillDesc() + ". The change from last month is due to " + getVariableBillDetails() + ".\n";
    return output;

  }
}