You can use a deque as a stack (First In, Last Out) or as a queue (First In, First Out). Lists are especially inefficient when adding/removing from the beginning of the list, but, for deques, it's a O(1) operation.

And it’s written in Java. Even though I’m not a huge fan of Java, it’s almost refreshing to see a new project claiming high performance that isn’t written in Rust or Go.