Mass submit approval process through apex code

/******************This method assign selected applications to selected user/queue*************/
public PageReference assignApplication() {
 PageReference pageRef = null;
 List requests = new List();
 SavePoint sp = Database.setSavePoint();
 try {
  for(ApplicationWrapperClass appWrapper : applicationWrapperList) {
   if(appWrapper.isSelected) {
    Approval.ProcessSubmitRequest req = new Approval.ProcessSubmitRequest( );
    req.setComments('Submitted for approval. Please approve.');
    req.setObjectId(appWrapper.application.Id);
    req.setNextApproverIds(new List{selectedUserOrQueue}) ;
    requests.add(req);
   }
  }  
  update applicationList;
  Approval.process(requests);            
  success = true;
  pageRef = Page.BulkAssignApplication.setRedirect(true);
 } catch(Exception e) {
  Apexpages.addMessage(new Apexpages.Message(Apexpages.severity.ERROR, e.getMessage() + '**' +e.getStackTraceString())); 
  Database.rollback(sp);
 }
 return pageRef;
}