JSF Session handling

Question

Hi,
I am using session variables in all my pages. If user tries to access the page after sometime, session expires and throws NullPointer Exception.
How to handle this. I know I have to use if it is not equal to null before using the session variable. what if it is null?
Any suggessions...
Thanks in advance...

Answer 1

Sorry . . .
One more thing . . . .
Since JSF loses parameters after a page reload you will have to store all the the values you want to "remember" in hidden fields. But . . . JSF autotmatically generate ID with form name at the begining. For example, if you want to pass the parameter: userId and the name of the form is: userForm, the name of the hidden field will be:
userForm:userId.
Now . . . this makes a problem extracting the hidden value by get parameter. Since on first call the paramter is named: userId, on a second call to the same page the parameter will be in the hidden field and named: userForm:userId.
In order to overcome this problem I wrote the following method:
  public static HttpServletRequest getRequest()
    HttpServletRequest request = (HttpServletRequest)FacesContext.
    getCurrentInstance().getExternalContext().getRequest();
    return request;
  public static String getRequestParameter(String key)
    return getRequest().getParameter(key);
  public static String locateRequestParameter(String partialKey)
    Enumeration enumeration = getRequest().getParameterNames();
    String key, value;
    while (enumeration.hasMoreElements())
      key = (String)enumeration.nextElement();
      if (key.indexOf(partialKey) > -1)
        value = getRequestParameter(key);
        return value;
    return null;
  }This is not a neat solution, since we iterate all the parameters . . .
You can also look here: http://www.jsftutorials.net/param.html
This is a "param" component, that keeps the URL with the parameter after the form is reloaded.
Thats it . . . ;-)