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Number Formatting Question

Posted on 2006-11-28
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Last Modified: 2013-11-24

I have a servlet that returns an ArrayList of floats to a jsp.   These floats represent percentages and print by default values like .02777777778 and .333333333.    

1.  I would like to format these to 2 decimals.  eg 2.78% and 33.33% respectivlely.  Question 1 is how to do that?

2.  Where is the appropriate place to format these? in the Servlet or JSP?

[Servlet] ----form----> [JSP]

my servlet code looks like:
   ArrayList list = new ArrayList();
    while(xxx){  loop and add #'s
        list.add(new Float( a/b));
    }
   form.setList(list);


JSP Code is:
<nested:iterate id="el" property="list">
   <nested:write property="el"/>
</nested:iterate>
0
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Question by:tmonteit
5 Comments
 
LVL 6

Expert Comment

by:SamsonChung
ID: 18029266
This might be of use to you

http://java.sun.com/docs/books/tutorial/i18n/format/decimalFormat.html

Also, do it in the Servlet. The less information you are passing between the pages the better...

0
 

Author Comment

by:tmonteit
ID: 18029486
Just so I'm straight how does it fit into my servlet code?

Say my form looks like this.

class myForm {
  private Float myData;
  // add getters / setters
}

In servlet;

  // How does the decimal formatter fit into here?
  // the form expects a Float, not a DecimalFormatter

  Float foo = 2.987373;
  form.setMyData(foo);

 
0
 
LVL 9

Expert Comment

by:owenli27
ID: 18029569
How about to add Strings into List instead of Float obj?

DecimalFormat formatter = new DecimalFormat("###.##");
while(xxx){  //loop and add #'s
    list.add(formatter.format(100 * a/b) + "%");
}
0
 
LVL 6

Expert Comment

by:SamsonChung
ID: 18030568
Float foo = 2.987373;
String pattern = "%";
DecimalFormat myFormatter = new DecimalFormat(pattern);
foo = myFormatter.format(foo);
form.setMyData(foo);
0
 
LVL 8

Accepted Solution

by:
reach2piyush earned 400 total points
ID: 18033777
It is done for display purpose(view), so that is the place it should be
either in your form bean or JSP

here are the choices:
 - in form bean, change your getter to give you the truncated value(java.text.NumberFormat or DecimalFormat)
 - in form bean, add another getter to give you the truncated value(java.text.NumberFormat or DecimalFormat)
 - in JSP. use JSTL Format Library <fmt:formatNumber maxFractionDigits=” 2”> {number}</fmt:formatNumber>
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