loancalc.java

webwork source

/*
 * WebWork, Web Application Framework
 *
 * Distributable under Apache license.
 * See terms of license at opensource.org
 */
package webwork.examples;
import webwork.action.ActionSupport;

import java.util.ArrayList;
import java.util.List;
public class LoanCalc
   extends ActionSupport
{
   private float presentValue = 1000;
   private float interestRate = 0.08f;
   private float instalment = 100;
   protected static final int MAXTERMS = 100;

   private List monthlyDues;

   public void setPresentValue(float presentValue)
   {
      this.presentValue = presentValue;
   }

   public float getPresentValue()
   {
      return presentValue;
   }

   public void setInterestRate(float interestRate)
   {
      this.interestRate = interestRate;
   }

   public float getInterestRate()
   {
      return interestRate;
   }

   public void setInstalment(float instalment)
   {
      this.instalment = instalment;
   }

   public float getInstalment()
   {
      return instalment;
   }

   public List getMonthlyDues()
   {
      return new ArrayList(monthlyDues);
   }

   protected void doValidation()
   {
      if (presentValue <= 0)
      {
         addError("presentValue", "must be > 0");
      }

      if (interestRate <= 0)
      {
         addError("interestRate", "must be > 0");
      }

      if (instalment <= 0)
      {
         addError("instalment", "must be > 0");
      }
   }

   protected String doExecute()
   {
      monthlyDues = new ArrayList();
      int month = 0;
      for (float rest = presentValue; rest > 0.0001f && month <= MAXTERMS; month++)
      {
         float interest = rest * interestRate / 12;
         float redemption = instalment - interest;
         float newRest = rest - redemption;

         if (newRest < 0)
         {
            monthlyDues.add(new MonthlyDue(month, rest, interest, rest, rest + interest));
         } else
         {
            monthlyDues.add(new MonthlyDue(month, rest, interest, redemption, instalment));
         }
         rest = newRest;
      }

      if (month > MAXTERMS)
      {
         addErrorMessage("Term is longer than " + MAXTERMS + " months!");
         return ERROR;
      }

      return SUCCESS;
   }

   public class MonthlyDue
   {
      MonthlyDue(int month, float presentValue, float interest, float redemption, float instalment)
      {
         this.month = month;
         this.presentValue = presentValue;
         this.interest = interest;
         this.redemption = redemption;
         this.instalment = instalment;
      }

      public int getMonth()
      {
         return month;
      }

      public float getPresentValue()
      {
         return presentValue;
      }

      public float getInterest()
      {
         return interest;
      }

      public float getRedemption()
      {
         return redemption;
      }

      public float getInstalment()
      {
         return instalment;
      }

      private int month;
      private float presentValue;
      private float interest;
      private float redemption;
      private float instalment;
   }
}