使用队列时出现java.util.NoSuchElementException

Question

I am using an if statement and when it runs it shows the exception java.util.NoSuchElementException

The code is shown below

if (BackgroundService.pendingQueue != null) {
                logger.error("Here is clear step next 2 ");

            BackgroundService.pendingQueue.remove();

            logger.error("Here is clear step next 3 ");
        }       
        logger.info("BackgroundService.pendingQueue="+BackgroundService.pendingQueue.
size());
        if(BackgroundService.pendingQueue.size() == 0){
            BackgroundService.pendingQueue.clear();
        }
        logger.info("BackgroundService.pendingQueue after task done is ="+BackgroundService.pendingQueue.size());
    }

The exeption is show between the "clear step 2" and "clear step 3" statements, on the BackgroundService.pendingQueue.remove(); statement. If you have a solution please reply with that solution

Answer 1

I can imagine your object is a kind of Queue. If you try to remove an object on an empty queue the exception NoSuchElementException is thrown.

So you need to check if the queue is not empty before trying to remove something:

  if(!BackgroundService.pendingQueue.isEmpty()){
    BackgroundService.pendingQueue.remove();
  }