problematic run-time errors

[Matt Riddoch]

I am as green as can be w/code, and have been kind of thrown in the fire with an assignment from school. It has been turned in, but I would like to better understand what issues I am running into. When I enter an integer for tax rate it loops output. When a decimal is entered this:

java.lang.NumberFormatException: For input string: "0.5"
at java.lang.NumberFormatException.forInputString(NumberFormatException.
java:48)
at java.lang.Integer.parseInt(Integer.java:477)
at java.lang.Integer.parseInt(Integer.java:518)
at Project.AccountIn(Project3.java:63)
at Project.appMain(Project3.java:40)
at Project3.main(Project3.java:17)

Sorry for the length but here is the problematic code: (A BIG THANKS!!)

import java.io.*;
 
public class Project3
{
   public static void main(String[] argv) throws IOException
   {
      Project app;
      app = new Project();
      app.appMain();
   }   // end main()
}
 
 
 
class Project
{
 
   BufferedReader stdin;
  
   String date, instring;
   int custnumber, itemcode, quansold, totquan, hicode, totitems;
   float taxrate, unitprice, discount, totnetprice, totdiscount;
   float hinetprice, extprice, netprice, avgquansold, taxamount;
 
 
   public void appMain() throws IOException
   {
      stdin = new BufferedReader (new InputStreamReader(System.in));
               // creates input string object
 
      ReportInit();
      AccountIn();
      while (itemcode != 0)
      {
         ProcItem();
      }
      lastcalc();
      rptOut();
 
   }
   void ReportInit()
   {
      totnetprice = totdiscount = hinetprice = totquan = totitems = 0;
      itemcode = 99999;
   }
   void AccountIn() throws IOException
   {
      System.out.print("\nPlease input the customer number(0 to stop):  ");
      instring = stdin.readLine();
      custnumber = Integer.parseInt(instring);
      System.out.print("\nWhat is today's date?  ");
      date = stdin.readLine();
      System.out.print("\nwhat is the tax rate? 0.X%?  ");
      instring = stdin.readLine();
      taxrate = Integer.parseInt(instring);
      
   }    
   void ProcItem() throws IOException
   {
         updatetotals();
         updatehighs();
         recordout();
   }
   void recordout() throws IOException
    {
       System.out.print("itemcode:  " + itemcode);
       System.out.print("quantity sold:  " + quansold);
       System.out.print("unit price:  " + unitprice);
       System.out.print("extended price:  " + extprice);
       System.out.print("net price:  " + netprice);
    }
 
   void updatetotals()
    {
       extprice = (quansold * unitprice);
       if (extprice > 400)
       {
           discount =(float)((extprice- 400) * 0.1);
       }
       {
           discount = 0;
       }
       netprice = extprice - discount;
       totnetprice = totnetprice + netprice;
       totdiscount = totdiscount + discount;
       totquan = totquan + quansold;
       totitems = totitems + 1;
    }
    void updatehighs()
    {
       if (hinetprice < netprice)
       {
           hinetprice = netprice;
           hicode = itemcode;
       }
    }
    void lastcalc()
    {
    avgquansold = totquan / totitems;
    taxamount = taxrate * totnetprice;
    }
    void rptOut()
    {
    System.out.println("\nFinal Output  ");
    System.out.println("\ncustomer #  " + custnumber);
    System.out.println("\ndate  " + date);
    System.out.println("\nTax rate 0.x%  " + taxrate);
    System.out.println("\nTotal net price  " + totnetprice);
    System.out.println("\nTotal discount  " + totdiscount);
    System.out.println("\nAverage quantity sold  " + avgquansold);
    System.out.println("\nTotal tax  " + taxamount);
    System.out.println("\nHighest net price" + hinetprice);
    System.out.println("\nand customer #  " + hicode);
    System.out.println("\nThank you and goodbye...");
    }
}

[edit]Add code tags. CR[/edit]
[ November 09, 2008: Message edited by: Campbell Ritchie ]

[Henry Wong]

java.lang.NumberFormatException: [I][B]For input string: "0.5"[/B][/I]
at java.lang.NumberFormatException.forInputString(NumberFormatException.
java:48)
at java.lang.[I][B]Integer.parseInt[/B][/I](Integer.java:477)
at java.lang.Integer.parseInt(Integer.java:518)
at Project.AccountIn(Project3.java:63)
at Project.appMain(Project3.java:40)
at Project3.main(Project3.java:17)

The Integer class is for integers -- which is for whole numbers. "1.5" is not a whole number, hence, not an integer.

Henry
[ November 08, 2008: Message edited by: Henry Wong ]

[Rob Spoor]

And please Use Code Tags.

[fred rosenberger]

many languages distinguish between integers (numbers with no fractional part) and floating point decimal numbers (numbers WITH a fractional part, although the fractional part may be zero - 5.0, for example). In fact, there are even different types for each of those, depending on how big a number you need to store vs. how much memory they use

I don't know the reason why they do this, but I assume it has to do with memory from back when memory was EXPENSIVE (my father talked about a computer Bell Labs bought where memory was $1 million for 1 megabyte).

In any case, as Henry has pointed out, you are using the "Integer" method to parse a string. Since it is expecting an integer to be represented in the string, it doesn't know how to handle a decimal point. Just like it wouldn't know how to handle "fred". If you want to parse a floating point, you need to use a different class than the Integer and it's parstInt() method.

[Campbell Ritchie]

I always thought it is because it means you can store different numbers in different formats, eg

Two's complement-Java int, long, short, byte.

Unsigned binary-Java char, C++ unsigned int, C# uint

IEEE754-Java float and double

Something else, eg C# decimal.

And that means that arithmetic on different kinds of numbers can be done differently with different precision, etc.

[Campbell Ritchie]

Originally posted by Rob Prime:
And please Use Code Tags.

I have added the tags, so you can see how much better the code looks. By the way: you are using an unusual indentation convention: your code should start farther to the right than the {}.

And (sorry I hadn't noticed it's your first post) welcome to JavaRanch

[Matt Riddoch]

Wow, thanks for the outpouring of help!! I am educating myself on the code tag issue, as I hope to become a regular contributor. I will crunch some of this info and hope for some better results!

[Campbell Ritchie]

You are welcome