List of Strings VS String Array VS Stringbuilder [duplicate]

Question

Which is the best one to choose to store list of string on the basis of performance.

Which one offers the best performance.

Thanks.

Answer 1

ArrayList is a good general purpose List and will usually out-perform an Array or LinkedList. Here is the breakdown in terms of time complexity (V is the type, i is an index):

       Type | add(V) | remove(V) | get(i) | 
-------------------------------------------
      Array |  O(n)  |    O(n)   |  O(1)  |
  ArrayList |  O(1)  |    O(n)   |  O(1)  |
 LinkedList |  O(1)  |    O(1)   |  O(n)  |

In general you can use this rule:

Array: Use if you know the exact number of elements and don't need to add or remove elements.

List: Use if you don't know the exact number of elements and need to add or remove elements.

StringBuilder is completly different. StringBuilder is a mutable String. You can think of it as List<Character>. In that sense, it is probably not what you need so to compare it to List<String> or String[] is probably not benificial.

Answer 2

List of String literals before java 7 will just consume your permgen Area which may led to JVM crash. So if you have too many String better go for Stringbuilder. Stringbuilder internally uses char array. However using Stringbuilder for storing list of String you may have to use special character for separation and then split() to retrieve back your list.

Better alternative would be to go for an String array. As mentioned earlier even Stringbuilder uses an char array. So if you are sure you want to store list of String this would be good option. But if this is the only goal I would say why not use ArratList... you don't have to bother about the size of the array.