Is there any java Deque that implements maxlen, like python collections.deque?

Question

Python's collections.deque has a maxlen argument, such that

[...] the deque is bounded to the specified maximum length. Once a bounded length deque is full, when new items are added, a corresponding number of items are discarded from the opposite end. [...]

I have been looking for a class that implements the Deque interface in Java, that does the same.

public ArrayDeque(int numElements) looks like numElements only initializes the deque to that size, but doesn't enforce it as a max length.

Answer 1

Probably not. LinkedHashMap has some facilities to build a cache with eviction policies, but that might be overkill for what you want. Just extend the Deque and add your custom logic ;-)

---

Edit:

class MyFixedSizeDeque<T> extends ArrayDeque<T>
{
   private int maxSize;
   public MyDeque(int size)
   {
      this.maxSize = size; 
   }

   @Override
   public void addLast(T e)
   {
      this.addLast(e);
      if(this.size() > maxSize)
         this.removeFirst();
   } 
}

My Java is a little rusty, and you might want to overload a few more methods (or switch to composition rather than inheritance) but I hope you get the idea...