Overriding struts validate method for showing custom error message

Overriding struts validate method for showing custom error message during FileUpload

 @SuppressWarnings("unchecked")  
      public void validate()  
      {  
       List<String> uploadErrors = (List<String>)getActionErrors();  
       if (getFieldErrors().get("upload") != null)  
       {  
        uploadErrors.addAll((List<String>)getFieldErrors().get("upload"));  
       }  
       for (String err : uploadErrors)  
       {  
        if ( err.startsWith("Enter the Error Message to be overridden"))  
        {  
         clearErrorsAndMessages();  
         addActionError("Enter new error message");  
         break;  
        }  
       }  
      }