I was reading Kathy sierra's OCP8 guide and found a line that says:
"ArrayDeque is like an ArrayList with better performance"
Now I am confused about where to use ArrayList and where to use ArrayDeque.
I also know that ArrayDeque is always resized to a power of 2. On resize, the capacity is doubled, so this might be a performance hit in some cases. But I want to know which is preferable between the two.
Help is much appreciated.
i would suggest use ArrayList over ArrayDeque on below cases
- Use an ArrayList if you need to access elements by index and you only
need to insert/delete at the end.
- Use an ArrayDeque as a stack, queue, or deque.
Insertion and Deletion in Both Collection.
ArrayList:
Worst-case O(n) because you have to shift elements. Insertion/deletion at the end is faster because there are fewer elements to shift. If you insert when the Arraylist is full, you have to copy the elements into a new larger array, which is O(n).
- Insertion at the end of an ArrayList takes amortized constant time.
This means that a sequence of n insertions into an initially empty
ArrayList has a worst-case runtime of O(n), so the average runtime
per insertion is O(1), although some insertions may be slower. This
is achieved by always increasing the array size by a constant factor,
because the total number of elements copied is the sum of a geometric
series.
ArrayDeque:
- Deletion at the front or back is O(1), and insertion at the front or
back takes amortized constant time. The JCF implementation does not
allow insertion/deletion by index (if it was allowed, it would be
worst-case O(n) because of shifting).
- Array deques have no capacity restrictions and they grow as necessary
to support usage.
- They are not thread-safe which means that in the
absence of external synchronization
- Null elements are prohibited in the ArrayDeque.
now answer is in your question. its totally depend on your requirement.after analysing you can easily predict.
for more please take a look