java - What is the Fastest way to reorder an array -

what fastest (realtime data processing application) way reorder (the new indices same) array in java:

e.g.: have got: double[] = new double[] {1, 234, 12,99,0};

i need swiftly: double[] b = new double[] {a[2], a[4], a[0],a[1],a[3]};

but maybe this efficient way anyway?

many feedback

i doubt can better current approach of

double[] b = new double[] {a[2], a[4], a[0], a[1], a[3]}; 

likely candidates other sequences might forms of arrays.copyof or arrays.copyofrange, minimum amount of work must here consists of:

• create new array
• random access each element in array

there's small chance might better specific read/write orders (to take advantage of cache lines), 1 guess reads entirely in order , writes entire in ascending order:

   double[] b = new double[a.length];    b[2] = a[0];    b[3] = a[1];    b[4] = a[3];    b[0] = a[2];    b[1] = a[4]; 

but don't have strong expectations of being noticeably better. if you're @ point you're trying eliminate or optimize on l1/l2 cache hits, it's time start micro-benchmarking, , real answer should experiment.