Warning in Java classes of Type Safe

[aby_8486]

Hi everybody i want to do like below but it shows the following warning .

Type safety: Unchecked cast from Object to
ArrayList<OfficeOfferLetter>

ArrayList<OfficeOfferLetter> allletters=new ArrayList<OfficeOfferLetter>();
allletters=(ArrayList<OfficeOfferLetter>) request.getAttribute("offerletters"):

In the above code OfficeOfferLetter is the serealizable Bean Arraylist;

& request.getAttribute("offerletters") return the object thats why it shows above warning.

so please suggest any solution ...

thank you