How to cast JSP request String to int?

[Thomas <li...@jps.net>]

How do you use a number from a request parameter in an equation using JSP?  In other words, 
How do you set the value of an int variable to the value of a numeric String variable?

I tried to do:

int Repeat1__numRows = 10;
if(request.getParameter("num_results")!=null) {
 Repeat1__numRows = (int)request.getParameter("num_results");
}

But the engine (tomcat 3.1 and jdk 1.3) says: 

Invalid cast from java.lang.String to int 

thanks for a tip,
Thomas

Re: How to cast JSP request String to int?

[Yun Sang Jung <na...@channeli.net>]

try below code!

try    {
Repeat1__numRows = Integer.parseInt(request.getParameter("num_results"));
} catch (NumberFormatExeption e)    {
}

  ----- Original Message ----- 
  From: Thomas 
  To: tomcat-user@jakarta.apache.org 
  Sent: Monday, August 21, 2000 3:36 PM
  Subject: How to cast JSP request String to int?


  How do you use a number from a request parameter in an equation using JSP?  In other words, 
  How do you set the value of an int variable to the value of a numeric String variable?

  I tried to do:

  int Repeat1__numRows = 10;
  if(request.getParameter("num_results")!=null) {
   Repeat1__numRows = (int)request.getParameter("num_results");
  }

  But the engine (tomcat 3.1 and jdk 1.3) says: 

  Invalid cast from java.lang.String to int 

  thanks for a tip,
  Thomas

Re: How to cast JSP request String to int?

[Rachel Greenham <ra...@enetgroup.co.uk>]

> Thomas wrote:
> 
> How do you use a number from a request parameter in an equation using
> JSP?  In other words,
> How do you set the value of an int variable to the value of a numeric
> String variable?

You can't just cast one type to a completely different type in Java. It may
seem inconvenient when you're starting out, especially coming from other
languages, but it's a good thing really. Trust me.

This is proper behaviour for Java, not version-specific and not
Tomcat-specific.

What you need is this:

int Repeat1__numRows = 10;
String num_results = request.getParameter("num_results");
if (num_results != null)
{
	try
	{
		Repeat1__numRows = Integer.parseInt(num_results);
	}
	catch (NumberFormatException nfe)
	{
		// Can't parse this as a number. Ignore and use default
		// (Obvious opportunity to do other things here, like show an error)
	}
}

-- 
Rachel