Optional methods of the Collection and Iterator interfaces. This class and its iterator implement all of the Therefore, it would be wrong to write a program that depended on thisĮxception for its correctness: the fail-fast behavior of iterators Throw ConcurrentModificationException on a best-effort basis. Presence of unsynchronized concurrent modification. Note that the fail-fast behavior of an iterator cannot be guaranteedĪs it is, generally speaking, impossible to make any hard guarantees in the Modification, the iterator fails quickly and cleanly, rather than riskingĪrbitrary, non-deterministic behavior at an undetermined time in the Method, the iterator will generally throw a ConcurrentModificationException. Is created, in any way except through the iterator's own remove The iterators returned by this class's iterator method areįail-fast: If the deque is modified at any time after the iterator Most ArrayDeque operations run in amortized constant time.Įxceptions include remove, removeFirstOccurrence, removeLastOccurrence, contains, iterator.remove(), and the bulk operations, all of which run in linear Stack when used as a stack, and faster than LinkedList Synchronization, they do not support concurrent access by multiple threads. They are not thread-safe in the absence of external Arrayĭeques have no capacity restrictions they grow as necessary to support But of course, there are implementations, such as LinkedList that actually do that.Resizable-array implementation of the Deque interface. To my knowledge, there is no interfaces that combines both interfaces (List and Queue). Simply change it to: List strings = new LinkedList() Īnd all of a sudden you can remove() objects by index or "by value". you change the underlying data structure to something that allows "random" remove actionsĪnd please note: your code shows a potential solution.you either have to "pop" all entries of the queue up to the one to remove, to then add them back.It only supports removing elements from head resp. The reason for that is simple: Queue is not a "random" access data structure. Every Queue implementation must specify its ordering properties. Other kinds of queues may use different placement rules. In a FIFO queue, all new elements are inserted at the tail of the queue. Whatever the ordering used, the head of the queue is that element which would be removed by a call to remove() or poll(). Queues typically, but do not necessarily, order elements in a FIFO (first-in-first-out) manner. Queue does not have a method to remove a specific object (at a certain index, or that is equal to some provided argument): Implements both interfaces of List and Queue.Ĭorrect. If you want to remove intermediate items, a linkedlist is not the most suitable. It seems that also a basic list could be suitable for what you want. The main question is why are you using a Queue/Linkedlist? You could change your code to: LinkedList queue = new LinkedList() Specified element (or equivalently, if this list changed as a result Lowest index i such that (o=null ? get(i)=null : o.equals(get(i))) More formally, removes the element with the If this list does not contain theĮlement, it is unchanged. Removes the first occurrence of the specified elementįrom this list, if it is present. I linkedlist is an implementation that implements the Queue interface but it also implements other interfaces. You should use a different data structure / collection object type.Īnother option would be to remove all the items of the queue and put them in another queue (except the item you want to remove).įinally, another would be to make your own queue implementation adding the extra method. The whole purpose of the queue data structure is to push items to the tail and remove them from the head (as a real queue works). The queue interface only allows you to remove elements from the head of the queue.
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