Quite a few problems with your code:
On Arrays.asList
returning a fixed-size list
From the API:
Arrays.asList
: Returns a fixed-size list backed by the specified array.
You can’t add
to it; you can’t remove
from it. You can’t structurally modify the List
.
Fix
Create a LinkedList
, which supports faster remove
.
List<String> list = new LinkedList<String>(Arrays.asList(split));
On split
taking regex
From the API:
String.split(String regex)
: Splits this string around matches of the given regular expression.
|
is a regex metacharacter; if you want to split on a literal |
, you must escape it to \|
, which as a Java string literal is "\\|"
.
Fix:
On better algorithm
Instead of calling remove
one at a time with random indices, it’s better to generate enough random numbers in the range, and then traversing the List
once with a listIterator()
, calling remove()
at appropriate indices. There are questions on stackoverflow on how to generate random but distinct numbers in a given range.
With this, your algorithm would be O(N)
.