Randomly iterate over ArrayList in Java

Question

Seems a very basic question. I\'ve an ArrayList al and I would like to iterate over it. Normally,

for(int i : al) {
    // some c         


        

Answer 1

You can use Collections.shuffle() on the list.

Note that this will shuffle the list itself, so if order is important you should make a copy of it (and shuffle the copy).

List newList = new ArrayList<>( oldList ) ;
Collections.shuffle( newList ) ;

Alternatively you could create a random array which has elements 0 - List.size()-1 and using those as indices to access "random" elements in the List.