Array vs ArrayList in performance

Question

Which one is better in performance between Array of type Object and ArrayList of type Object    Assume we have a Array of Animal objects   Animal animal    and a arraylist   ArrayList list lt Animal gt   Now I am doing         animal 10     and     list get 10  which one should be faster and why

User · Answer

Arrays are better in performance  ArrayList provides additional functionality such as  remove  at the cost of performance

User · Answer

I agree with somebody s recently deleted post that the differences in performance are so small that  with very very few exceptions   he got dinged for saying never  you should not make your design decision based upon that   In your example  where the elements are Objects  the performance difference should be minimal   If you are dealing with a large number of primitives  an array will offer significantly better performance  both in memory and time

User · Answer

It is pretty obvious that array 10  is faster than array get 10   as the later internally does the same call  but adds the overhead for the function call plus additional checks   Modern JITs however will optimize this to a degree  that you rarely have to worry about this  unless you have a very performance critical application and this has been measured to be your bottleneck

User · Answer

From here      ArrayList is internally backed by Array in Java  any resize operation   in ArrayList will slow down performance as it involves creating new   Array and copying content from old array to new array         In terms of performance Array and ArrayList provides similar   performance in terms of constant time for adding or getting element if   you know index  Though automatic resize of ArrayList may slow down   insertion a bit Both Array and ArrayList is core concept of Java and   any serious Java programmer must be familiar with these differences   between Array and ArrayList or in more general Array vs List

User · Answer

When deciding to use Array or ArrayList  your first instinct really shouldn t be worrying about performance  though they do perform differently   You first concern should be whether or not you know the size of the Array before hand   If you don t  naturally you would go with an array list  just for functionality

[java] Array vs ArrayList in performance

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