まあ問題はlistでやると使えないメソッドがかなりあると void addFirst(E e) void addLast(E e) void clear() E getFirst() E getLast() boolean offer(E e) boolean offerFirst(E e) boolean offerLast(E e) E peek() E peekFirst() E peekLast() E poll() E pollFirst() E pollLast() E pop() void push(E e) E removeFirst() boolean removeFirstOccurrence(Object o) E removeLast() boolean removeLastOccurrence(Object o)