Sort an array of primitives with a custom comparator and without converting to objects

Question

What\'s the simplest way to sort a primitive array in Java with a custom comparator (or key) function and without converting to an array of objects (for performance †).

Answer 1

You can just build your own compare functions , and use one of the sort algorithms

easiest and slowest: BubbleSort ( O(N^2) ).

hardest but fastest : MergeSort( (O(Nlog(n) ) .

now in both algos you have the part that asks if A > B , in this part you should put your compare func.

boolean compare(int x, int y){
     if(/* your crazy compare condition */)
         return true;
     else return false; 
}

example in bubble sort :

    procedure bubbleSort( A : list of sortable items )
   repeat     
     swapped = false
     for i = 1 to length(A) - 1 inclusive do:
       /* if this pair is out of order */
       if compare(A[i],A[i-1]) then // Notcie the compare instead of A[i] > A[i-1]
         /* swap them and remember something changed */
         swap( A[i-1], A[i] )
         swapped = true
       end if
     end for
   until not swapped
end procedure

hope this helps